Isil fighters can no longer escape Syria to carry out attacks in Europe such as those that took place in Paris and Brussels, according to a chief in the US-led coalition against the terror group.

“Terrorist combat units” intent on wreaking havoc in Europe can no longer leave Isil’s de facto Syrian capital of Raqqa via Turkey, said Brett McGurk, special presidential envoy for the global coalition against Isil.

“Not too long ago, what they [Isil] would do is plan a terrorist attack in Raqqa, they would train a unit – kind of a terrorist combat unit – they would then infiltrate out… and go conduct an attack such as in Paris or in the Brussels airport” he said. “That’s what they used to do, and they were developing that capacity. They cannot do that anymore.”