The terror threat to Europe will only increase this year, experts have warned, as growing numbers of foreign fighters return home with “high tech” weapons knowledge learned on the battlefield.

Scores of jihadists are expected to trickle back to the UK and the continent, bringing with them skills acquired in Syria and Iraq, such as the weaponising of drones and the industrialised manufacture of car bombs and IEDs, according to a new report from defence analysts Jane's Terrorism and Insurgency Centre (JTIC).

“Foreign fighters returning to Europe will provide critical skills that will help an increasing number of operational Islamist networks conduct more complex attacks,” Otso Iho, the report’s author, said.

“These skills include the construction of viable IEDs - learned in Iraq and Syria where the Islamic State (Isil) has produced IEDs on an industrial scale - expertise in assault weapons, and the use of new weapons types or technologies such as drones.”