PARIS (AFP) - French President Francois Hollande on Thursday pledged his country's "support" to forces battling Islamist militants in Iraq amid growing Western concern over an advance by Islamic State (IS) fighters.

"The President confirmed that France was available to support forces engaged in this battle," Mr Hollande's office said in a statement, after the French leader spoke about Iraq by telephone with the head of the Kurdistan Regional Government, Massud Barzani.

Mr Hollande did not specify what form the "support" could take.

Mr Hollande and Mr Barzani "expressed their willingness to cooperate to block the offensive carried out by the Islamic State in the north-east of Iraq," the statement added.

At France's request, the UN Security Council is to hold an emergency meeting on Iraq later Thursday, after Islamist militants seized the country's largest Christian town.

IS, which proclaimed a "caliphate" straddling Syria and Iraq in late June, moved into Qaraqosh and other towns overnight after the withdrawal of Kurdish peshmerga troops, residents said.

Religious leaders said IS militants have forced 100,000 Christians to flee and have occupied churches, removing crosses and destroying manuscripts.

"The persecution by this terrorist group of religious minorities, in particular Christians and Yazidis, is an extremely serious crime," the statement from Mr Hollande's office said.

He reiterated that France was prepared to "offer asylum to those people who want to leave Iraq and who have a solid connection to our country".

Mr Hollande said that France would push the UN Security Council to "mobilise the international community against terrorism in Iraq so that help and protection can be offered to all people in danger".