When Shazia Mirza first got into comedy she imagined it would be liberating, the stage offering a freedom that, growing up in a repressed Muslim household in Birmingham, she could only dream of. Three weeks after September 11, the world was still coming to terms with the terrorist attacks on New York and the Muslim community was regarded with widespread suspicion. Mirza stepped up to the mic and uttered her now infamous, deadpan opening line: "Hi, I'm Shazia Mirza. At least that's what it says on my pilot's licence ..."

There was a sharp intake of breath before the audience in the London venue erupted with laughter. With one sentence, Mirza had tapped into the zeitgeist, deftly reflecting the tragic preoccupation of the moment. The world sat up and took notice. Dressed in a traditional hijab of a headscarf and long tunic, she would joke: "Does my bomb look big in this?" and "Anyone with a moustache is a target now. My mum was attacked." Yet what to the outside world seemed like a great triumph, for Mirza, less than a year into her fledgling career, was almost her undoing. She found herself labelled an anomaly, a novelty, and perhaps most cruelly, by her peers in stand-up comedy, little more than a flash in the pan.

Seven years on Mirza, now 34, says she is only now beginning to find her feet. Sitting in a tucked-away corner of the Groucho Club, a favoured London haunt of celebrities and media types, a weariness descends as she reflects on those early days. Not only did her overnight success spark jealousy in the comedy world, with Mirza being dismissed as a gimmick - rather unfairly given that she had won best new act at the London Comedy Festival earlier that year - but her devout Muslim parents struggled to understand why their science teacher daughter was living a double life as a comedian. She was heavily criticised by the traditional Muslim community and received hate mail: one man threatened to throw acid in her face to stop her performing.

Caught off guard by all the attention, Mirza felt trapped between a rock and a hard place. Instead of being elated, she found herself hating every minute of it. "I felt like a novelty act," she says. "The comedy world thoroughly despised me for getting all that attention but not being a great comedian - no comedian gets reviewed to the extent I was after six months. I didn't have a chance to develop, I didn't have a chance to breathe.

"It's showbusiness: it's shallow and bitter. People were horrible to me and it hindered my progress. They didn't give me gigs because they were jealous, so I couldn't develop and get good as fast as I would have liked to. I was being criticised horrendously by the comedy world, people saying I'm not going to last, I'm a flash in the pan, I'm just a gimmick. I remember thinking: This isn't why I began doing comedy. I didn't want to be famous overnight. I didn't want to be famous for being a Muslim woman that wears a burkha. I just want to be a comic.'"

Mirza kept her head down and took "any old rubbish gig", often travelling for miles to do shows for free. Unable to get any stage time in London, she went to the Edinburgh Festival Fringe in 2002. "I thought if I did half an hour every night for 30 nights I'd become a better comic," she says. "The downside was I was reviewed and told I was rubbish. I lost all my confidence reading so many negative things about me. There was also a sense of what people wanted me to be. I think white middle-class Britain had an agenda: The first Muslim woman in stand-up comedy? Right, I want her to explain 9/11, tell us who killed Benazir Bhutto and explain why Muslims are the way they are.' But that's not what I want to do."

Even so, to her horror, Mirza found herself conforming. "I began pandering to it and doing what they wanted me to do," she admits. Soon she found herself pigeonholed. The same repetitive descriptions cropped up: "Britain's first female Muslim comedian", "the British-born female Asian comedian", "the Muslim female comedian from Birmingham" - with the obligatory "feminist", "provocative" and "controversial" thrown in for good measure - and sometimes just "the female comedian". At the latter Mirza descends into raucous laughter. "I don't have a penis, I really am a woman," she insists fervently. "Although, perhaps people think I'm a transvestite."

Despite her cheery demeanour, it's clear Mirza finds such tags hugely frustrating. "I don't like labels - apart from Gucci," she quips. "Those labels don't tell you anything about me or anything about my show. You would be misled into thinking I'm going to give some inside or political view into how Muslims in Britain today live, but actually, I'm not your stereotypical Muslim woman."

Another problem was being taken seriously in the male-dominated world of stand-up comedy. "A lot of people who come into comedy say: It's because I'm an outsider. I was bullied at school/I was ginger/I have a disability/I'm fat/I'm anorexic,'" says Mirza. "When I came into comedy, I felt like an outsider in a world of outsiders. There were no Asian women, there were no Muslim women. It was a blokey world - and they didn't know how to deal with me."

After the lows, Mirza focused on touring abroad. "I was able to develop with a supportive audience. I wasn't getting that chance here," she says. "People thought I wouldn't last but now they take me seriously. I feel like I've had to work three times as hard, not just as male comics, but other female comics, to prove myself. First of all it was my culture and upbringing that stopped me from being a comic, then it was the comedy world. Criticism is good, though. They may break you, but ultimately, they make you."

THE eldest daughter of Pakistani immigrants - Mohammed, a car salesman, and Sarwat, a teacher, who moved to Britain in 1965 - Mirza grew up in Birmingham. It was a strict upbringing. As a teenager Mirza, frustrated with parental restrictions, wrote in her diary: "I hate my mum and dad, I want to kill them and if I don't kill them, I'll kill myself.' She first realised she was funny aged nine and would tell everyone - to the chagrin of her parents - that she wanted to be an actress. "My mum would say: Don't show us up again. It's a doctor, a dentist or a lawyer.' I used to think: I want to be Joan Collins.'"

She grew up watching Larry Grayson, Kenny Everett and Frankie Howerd on television - "All the gay comedians, although I didn't know they were gay," she says, laughing - but never thought being a comedian was an option for her. "I used to think that's what white men did, and that I'd never be able to do that," says Mirza. "When you think something is not a possibility, you shut it out of your mind."

After studying biochemistry, Mirza worked as a science teacher in the deprived Tower Hamlets area of east London. "I used to stand in front of a class of 16-year-old boys who weren't interested in science and didn't want to learn," she recalls. "They used to leave my classroom through a window. I locked the doors to keep them in. They used to say: F*** miss, this is boring.' My job was to somehow keep them interested. So, what I was doing in the classroom, I took to the stage. As it turned out, the comedy gigs were much easier. No-one ever sat in one of my gigs and said: F***, this is shit.'" Or climbed out of a window to escape? She laughs. "I've never had to lock an audience in."

In 2000, she did her first gig at 2am in a Brixton pub. There was no microphone or stage: just Mirza and an audience of 50 men. Afterwards, she received a standing ovation. Mirza avoided telling her parents for nine months, doing gigs in secret across London. It was only when she won the London Comedy Festival in summer 2001 she told them. They reacted with shock and horror. Neither understood what stand-up comedy was. To them it was akin to prostitution.

Her parents, she says, wanted her to become a doctor and be married by 20. Yet, here she is: 34, unmarried, childless - but successful at what she does. Have they come around to the idea yet? Mirza shakes her head. "They still want me to get married, but now they are saying the reason I'm not married is because I'm a comedian. Men don't want a funny wife."

Her mother has only been to see her perform once. Most of the jokes, says Mirza, went straight over her head. Her father hasn't seen her live, preferring to watch his daughter on television. He's 70 now. Does Mirza think he might mellow in his old age and relent? "I really don't," she says. "He's had two heart attacks. I don't want to bring him to a show and kill him off." Perhaps it's just as well, given that Mirza often uses her family as material. Sometimes it's raw and close to the bone: she's joked in the past that her mother is tolerant of her father's use of prostitutes. "They know I talk about them - but they don't know what I say," she says, her brown eyes dancing mischievously. "Comedy is about truth. If you tell the truth, it is going to be funny."

Unsurprisingly, her parents hoped comedy was just a phase. "People would stop my mum in the street and say: Oh, we saw your daughter on TV,' and she would reply: No, no, no, she is really a biochemist. The comedy is just a hobby.' My parents are confused and slightly concerned. It's such an alien thing. There are very few Asian comics in Britain. You could probably count them on your right hand. It's the same in America. It's a cultural thing: comedy has always been part of black history - Bill Cosby, Richard Pryor - part of Jewish culture - Woody Allen - and part of British culture, but there is no history of Asian comedy and certainly no history of Muslim comedy."

Things are only slightly easier now she's famous. "They love success in Asian families," says Mirza. "They don't care what you do. I could be a stripper - but they would want me to be the best stripper. Starting out, I thought there's no point in me telling them I'm a comedian, because they only want to hear it when I'm a successful one. Asian people are shallow: they don't care what you do, but if you are doing well, they will shout it from the rooftops. My daughter, I don't know what she does, but she's great at it.'"

Mirza is often described as "a practising Muslim", something which baffles her. "I'm not really," she says. "I practise a lot - I don't know if I'm any good." She doesn't eat pork or drink alcohol, but is less strict in other elements of the Muslim faith. "I don't cover my head, I don't pray five times a day, I wear quite revealing clothes sometimes. I've never ever said I was a practising Muslim: it's misleading. People will think I pray five times a day, keep my fasts, that I've never drunk alcohol, taken drugs or gone out with men. It's not right to say that because it's not true."

The misconceptions don't stop there. A downside to her apparently resolute single status - "I don't do jokes about sex because I have never had it," is one such offering - is inadvertently creating intrigue about her sex life. "Is she a lesbian? Is she straight?" says Mirza, taking up the thread. Not to mention being the Britney Spears of British comedy. "Yeah, but she was 17 when she said she was a virgin, not 34, which is just not cool. I make loads of jokes about sex, so the ones about virginity are not alone. I do a routine about anal sex and one about my parents. They have said all my life: Don't go near men, don't look at them, if we catch you with a man, we'll kill you.' Now they say to me: Where are your children? Where are your grandchildren?' I mean, how did they get from there to there? Now it's: F*** anything, f*** anything you can. Eat pork, get drunk and f*** Salman Rushdie.' I joke they are so desperate now they would even take a ginger."

Her ideal man is Simon Cowell. She also has a knack for developing crushes on gay men. "I've never played the field," she says fervently. "But I do have someone, yeah. He is really nice. He is straight, obviously, but has a lot of gay qualities - and that's what I want. He's really nice and very funny, but not a comedian. He is Irish and was brought up Catholic - so I'm waiting, obviously, for him to convert to Islam. He's a lot older than me, a photographer and architect." She stops short of giving his name. "No, he's very private," says Mirza, grinning like a Cheshire cat.

Petite with huge eyes framed by long lashes and shiny shoulder-length hair, Mirza has no airs and graces. Wholly unstarry, she's a girl's girl who goes shopping in Primark, appears baffled at making the top 20 of the Muslim Women's Power List 2009 ("It's ridiculous. How am I powerful? I couldn't get you a table at McDonald's.") and admits to picking her nose in public.

It takes a lot to faze her (she once continued her Fringe show out in the street after a fire alarm) and jokes about conforming to her parents' desire for her to have arranged marriage like they did ("Yes - I'll be arranging it myself," she quips).

In 2007, Mirza made a BBC Three documentary titled F*** Off, I'm A Hairy Woman, for which she didn't wax, shave, pluck or bleach her excess body hair for seven months. She still gets emails from women - and some men - asking for tips and as to whether laser hair removal really works. Even so, Mirza balks at the idea of being considered a role model: "It's another label," she exclaims. "Besides, I will only let people down. They will say: Oh, she's such a brilliant girl' and then see me pissed in some bar one night and think: What a shame.'"

Her material is mostly autobiographical: her upbringing, observations and current obsession - blogging. "The blog is fame for shy people. Even the most retarded, reclusive person can write a blog and be famous. I read one the other day about a girl who went to the zoo and saw a koala ..."

Although she's had her fingers burned in the past, Mirza rails against convention, not least including the word "Paki" in her routine, mirroring the black comedians who use "nigger" to diffuse the term. "People have been conditioned not to laugh at racism, that they mustn't joke about beige people," she says. "I use the joke someone shouted: Oi Paki, go back to India.' It was Prince Harry." Similarly she remains attuned to capturing life's darker undercurrents: "The only way Heather Mills could redeem herself now is to find Madeleine McCann" is one such offering, referring to the former model's fall from grace after her divorce from Sir Paul McCartney.

Mirza, who writes a column for The New Statesman, admits to honing ambitions to star in a comedy film ("I've written some gags for a film but I'm not in it. I would like to be in one"). She claims to be beyond worrying about what people think of her.

"Everyone is always telling me what I should be, what is expected of me: you are not funny enough, you're not Muslim enough; you're not brown enough, you're not feminine enough, you're not pretty enough, you're not thin enough," she says.

"Everyone has lost their individuality, especially in comedy. The things that make you unique, are the things that are not perfect. They are your nuances: you're fat, you're hairy, you're brown - don't be afraid of the things that make you funny. I've learned to stop believing what everyone says about me." Smart, fearless and funny: that crack was comedy's glass ceiling being broken.

Shazia Mirza is at Eden Court, Inverness on June 21; Tolbooth, Stirling on June 24; Lemon Tree, Aberdeen on June 25; and Dundee Rep on June 26. Visit www.shazia-mirza.com