Everything seems normal as the passengers stream out of a routine flight from a Middle Eastern country after landing at a major Turkish international airport.

But as they cross the air bridge from the plane into the airport, two plainclothes Turkish police — on the lookout for jihadists on their way to Syria — scrutinise their appearance and behaviour.

They check the passengers’ passports and detain two men who arouse suspicions after saying they are travelling on to the city of Adana, in southern Turkey.

The country has long been under pressure to do more to thwart the transit of jihadists across its territory to war-torn Syria. Thousands are believed to have taken commercial flights to Turkish airports before heading overland to Syria to fight alongside Islamic State (IS) militants.

But Ankara insists it is now doing all it can to tighten border security and said Western states should do more to prevent the jihadists from leaving for Turkey in the first place.