Terrorists are more likely to attack European countries as a result of a controversial deal to allow Turkish citizens to travel across the continent without visas, EU leaders have admitted.

Foreign terrorists and organised criminals are “expected” to seek Turkish passports to reach continental Europe “as soon as” the visa waiver program comes into force, a European Commission report said.

The disclosure came as Sir Richard Dearlove, the former head of MI6, warned that the decision to give Turkey visa-free travel is “perverse” and compared it to “storing gasoline next to the fire”.

Sir Richard also said that the EU will face a "populist uprising" if it fails to control migration.

Turkey’s 75 million citizens will have the right to enter the Schengen zone for up to 90 days at a time with biometric passports from the end of June if Ankara passes key anti-corruption and terrorism reforms.

The decision was part of a hastily-assembled deal brokered by Brussels to halt the flow of migrants from Turkey to Greece.

However, the European Commission report acknowledges the “increased mobility into the Schengen area of criminals and terrorists who are citizens of Turkey, or who are foreigners based in Turkey.”