Intelligence on suspected ISIS sympathisers has been increased as the FBI warn of more terror attacks on Europe.

Gardai and the Army have scaled up their monitoring of the small group of suspected ISIS supporters in Ireland, the Irish Independent reports.

Senior security advisers are worried about the number of 'lone wolf' attacks on mainland Europe.

Specialist sections of An Garda Siochana and the Army have been keeping a close watch on listed suspects to determine whether they have attempted to attract fresh support from young people living here or encouraged others to become involved in violence.

Yesterday James Comey, director of the FBI, said as ISIS lose ground in Syria, the terror group will try to infiltrate western Europe and the US to carry out attacks.

Speaking in New York he said: “At some point there’s going to be a terrorist diaspora out of Syria like we’ve never seen before."

Mr Comey said the future of this threat has already been seen on the streets of France and Brussels.

Just two days ago a would-be jihadist who was under police surveillance murdered an 84-year-old priest who was saying mass.

Adel Kermiche, 19, and his accomplice took hostages in a church on the outskirts of Rouen before being killed by police.

The killer was wearing an ankle tag and was known to intelligence services in the area.