HAND-HELD metal detectors are being used at a secondary school to ensure pupils are not bringing knives onto the premises.

Bosses at Unity College in Burnley said they will use the devices when acting on information from other students and could carry out spot checks, but stressed the measure was a precaution and not intended to 'alarm parents or students'.

The scheme has the backing of Burnley politicians. The town's MP Julie Cooper said schools have a duty to take measures to safeguard pupils.

However union bosses warned the use could be 'disproportionate' and said they were unaware of other schools taking the measure.

In a letter to parents, headteacher Sally Cryer said any children caught with knives would be permanently excluded.

She said they have had the devices for several years but they were rarely used. She added the school had no issues with weapons and would not be screening children as they came into school.

Mrs Cryer said: "The spot checks are not related to any specific incident but are rather a precautionary measure aimed at ensuring that the college remains a safe learning environment for students and staff."

She said the devices would be used as a last resort if there was a suspicion a child had a knife.

"I do not recall the last time we had to do it. Children are fully aware that if they bring a knife into school they will be excluded," she said.

"It is to ensure every child's safety is guaranteed. I take the safety of our pupils in school very seriously. It is a precaution to ensure we never have a knife on the premises."

In 2014 education watchdog Ofsted rated Unity College's work to keep students safe and secure as 'outstanding'.

In guidance issued by the Department for Education (DfE), schools can require pupils to undergo screening by a walk-through or hand-held metal detector even if they do not suspect them of having a weapon and without the consent of the pupils.

Of 13 schools asked by the Lancashire Telegraph whether they use the devices, the 10 who responded said no.

Sam Ud-din, Lancashire division secretary for the National Union of Teachers, said the school, which has 900 students, was going beyond what was required of it legally and he knew of no other school in the area taking the step.

He said: "If it is not a proportionate response based on common sense it will likely generate distrust and unrest.

"If pupils feel they are not being treated fairly it could push things the other way.

"It is not proportionate unless it is based on a specific threat. If they are saying there is no specific threat and they are doing it as a precaution, where does it end?

"If the fear is that one or two children might deliberately do it they should act against those individuals and they should not be imposing a blanket policy on every child. That is not good behaviour policy to treat every child as a potential criminal."

Mrs Cooper said the precautions being taken followed DfE guidelines and reflected the fact that schools have a duty to take all reasonable measures to safeguard pupils in their care.

She said: "I feel sure that we can trust the professional judgement of the school leadership team to implement these measures in a sensitive and proportionate way.

"Fortunately serious security issues at our schools are rare, but history tells us that they do occasionally occur and I feel certain that parents would support schools in their efforts to keep their children safe."

Cllr Mark Townsend, leader of Burnley Council, said although it was 'sad and disappointing' that schools had to take this measure he was sure they were doing it in the best interests and for the safety of the pupils.

Cllr Gordon Birtwistle, the Lib Dem group leader, said the safety of students was paramount and said he did not object if handheld devices would prevent a serious incident.

"It is a sorry state of affairs if students are going to school with knives. It is awful to think about," he said.

He said he had heard of similar measures being taken at a couple of schools in Burnley around 10 years ago.

Brendan Conboy, headteacher of Thomas Whitham Sixth Form in Burnley, who was until recently helping lead Hameldon Community College, said: "It is not something I have considered in my 15 years as a head.

"It would be a really sad day if we had to go that far. If we had them we would use them very rarely.

"In 15 years I have had two or three occasions (when a child has been found with a weapon). Children know the implications and that they would be permanently excluded."

Helen Stead, headteacher of Fearns Community College in Stacksteads, said: "It is not something we have an had an issue with and not something we have considered using."

Figures revealed by the police via a Freedom of Information request last year showed eight pupils were found with knives in schools across Lancashire.