Foreign Secretary William Hague has issued a renewed appeal to Iraq's political leaders to set aside their differences and unite to combat the threat from Isis extremists.

Following talks with Kurdish leaders in Irbil in northern Iraq, Mr Hague re-iterated his call for the formation of a broad-based government drawing together politicians from across the sectarian divide.

"My message is the need for unity in facing this danger, and the need to form an inclusive new Government as soon as possible," he said.

"We hope everyone, Shia, Sunni and Kurd will do what they can to make that happen. We believe as friends of this country that this is urgent and vital work."

He paid tribute to the efforts of Kurdish forces in resisting the advance of Isis (the Islamic State of Iraq and the Levant) following the sweeping gains made by the extremists.

"Kurdish security forces are playing an important role in holding Isis back, and have already made many sacrifices in this vital struggle. We stand with you in rejecting the vile crimes of terrorists," he said.

Mr Hague yesterday held talks in Baghdad with prime minister Nouri al-Maliki where he warned that Iraq was facing an "existential threat".

Mr Maliki - who is criticised for favouring the interests of the Shia population - is resisting calls to form an emergency administration, saying it would amount to a "coup against the constitution" after he won elections in April.