More than 100 US marines and special forces landed on Mount Sinjar in Iraq on Wednesday to organise an escape route for 30,000 Yazidi civilians threatened by Islamic extremists and worn down by hunger and thirst.

The force flew in on V-22 Osprey tilt-rotor aircraft that can land vertically. They joined a small number of American special forces soldiers who have been on the mountain for some days, assessing the military and humanitarian situation and guiding US air strikes against Islamic State (Isis) fighters encircling the mountain.

A handful of British SAS soldiers are also in the area to “gather intelligence” a British official said.