It is “indisputable” that terrorists have entered Europe posing as refugees, and some of them will target the UK, Europol has warned.

The continent’s law enforcement agency said in a report that terror groups were determined to continue attacks against European countries, especially as militants return to Europe after being driven out of Iraq and Syria.

Breitbart London reported on Friday that Europol had raised concerns about terrorists using car bombs to attack targets in Europe, a tactic jihadists have so far only used in the Middle East.

There has already been one foiled car bomb plot in Paris, with French police arresting two suspects after a car containing gas cylinders was discovered near Notre Dame cathedral.

Europol has also said that recent terrorist atrocities in Paris and Brussels have only strengthened the resolve of Islamic State to attack Europe.

“France remains high on the target list for IS aggression in the EU,” the report says. “But so too do Belgium, Germany, the Netherlands and the UK.”

“Estimates from some intelligence services indicate several dozen people directed by IS may be currently present in Europe with a capability to commit terrorist attacks, and that there are indications that IS has been preparing terrorist attacks in Europe since 2013.”

The report added that it was “indisputable that some [terrorists] have entered the EU posing as refugees”.

Several of the jihadists who committed the mass terror attack in Paris last November were discovered to have entered Europe through Greece in the midst of the migrant crisis, posing as refugees.

Greek authorities admitted that at least two of them had entered the continent via the island of Leros, registering as asylum seekers.

A few months later, two men were arrested in the Austrian city of Salzburg on suspicion of planning further attacks in the French capital.

They had also entered Europe through the Greek island of Leros at the same time as the Paris attackers.