Defence sources confirmed last night that the UK has stepped up efforts to prevent another coalition pilot being taken by the enemy should their aircraft be shot down.

The Joint Personnel Recovery (JPR) units will be 12-man teams. The troops are poised to board armour-protected Chinook helicopters and will be accompanied on rescue missions by jets providing 'top cover'.

A Special Forces source said: 'We may have very little time to respond but we can go in with a lot of firepower and, depending on where he lands, we can hopefully get a downed pilot back before he is snatched by IS. This could be on the ground in Syria or in parts of Iraq occupied by the insurgents.