Europe must prepare for a fresh influx of Isil jihadists fleeing Mosul as the army moves in on their last Iraqi stronghold, the EU’s security commissioner has warned.

"The retaking of the IS's northern Iraq territory, Mosul, may lead to the return to Europe of violent IS fighters," Julian King said. 'This is a very serious threat and we must be prepared to face it.”

Some 2,500 EU nationals are currently fighting alongside Islamic State of Iraq and the Levant (Isil), he added, and that if even a handful return it would pose a "serious threat that we must prepare ourselves for".