Iraqis flee their towns and villages from Islamic State militants

Tens of thousands of Yazidi Iraqis flee their towns and villages from Islamic State militants, who have now surrounded them on a mountain in Sinjar

Islamic State militants extended their gains in northern Iraq on Thursday, forcing tens of thousands of Yazidi Iraqi's to flee the town of Sinjar for surrounding mountains.

Some of the many thousands trapped by Islamic State fighters on Sinjar mountain have been rescued in the past 24 hours, a spokesman for the UN Office for the Coordination of Humanitarian Affairs said, adding that 200,000 had fled the fighting.

"This is a tragedy of immense proportions, impacting the lives of hundreds of thousands of people," spokesman David Swanson said by telephone.

Many of the displaced people urgently need water, food, shelter and medicine, he said. A spokesman for the U.N. agency for children said many of the children on the mountain were suffering from dehydration and at least 40 had died.