11 held over terror offences last year

Jihadist attacks accounted for one in six of all terror attacks, with two-thirds of attacks being linked to nationalist or separatist disputes.

There were 205 foiled, failed, or completed attacks in 2017, a jump of 45% on 2016. Ten of the 33 jihadist attacks were completed, resulting in 62 deaths — 35 of them in Britain, 16 in Spain, five in Sweden, three in France, two in Finland, and one in Germany.

“Similarly to 2016, nearly all reported fatalities and casualties were the result of jihadist terrorist attacks,” said the report.

Of the 975 terrorist arrests across the union in 2017, the bulk were categorised as jihadist.

There were 11 terror arrests in Ireland, eight of them republican-related and three jihadist.

The biggest number of jihadist arrests were in France (373), Spain (78), Germany (52), Belgium (50), and the Netherlands (28).

In Ireland, the Garda threat level remains at moderate — meaning a jihadist attack is possible, but not likely.

Gardaí and the Defence Forces have run a number of live operations, including in Dublin and Shannon Airport, simulating a terror attack.

The Europol report said there had been 88 security-related incidents in the North — 58 shootings and 30 bombing incidents. They included five dissident attacks on national security targets, including the shooting and serious injury of a police officer in Belfast.

Europol director Catherine de Bolle said the threat of jihadist terror “has increased considerably” since 2006.

She said no other type of terror attack has been as lethal and has had “such an impact on society as a whole as those committed by jihadist terrorists”.

The report said that while there has been an increase in the frequency of jihadist attacks, there has been a decline in the sophistication of the attacks.

Security agencies in Europe, including in Ireland, have expressed concern at the possible threat posed by returned fighters from Syria and Iraq.

The Europol report said an estimated 1,500 foreign fighters have returned to their homes and 1,000 have been killed, with Belgium, Germany, France, and Britain being the main source countries.

An estimated 30 Irish citizens went to Syria and Iraq to fight with various groups, and an estimated five of them have died, including one fighting for Islamic State (IS).

“As IS gets weaker, it has been urging its followers to carry out lone actor type attacks in their home countries,” said the report.

It said the terror group has urged followers to specifically target civilians, which it said was posing a “significant challenge” to the authorities in terms of setting up counter-measures.

It said that attackers in Europe have tended in the main to be lone individuals who have not been to a conflict zone.

They may be inspired by terrorist propaganda but often have no direct link with them, it said.

The report said they may have been known to the police, but not for terrorist activities.

It said IS has often been quick to claim responsibility for attacks, despite a lack of substantiating evidence.

It said many IS sympathisers have moved from Facebook and Twitter to Telegram.

The report said violent right-wing extremism was expanding in Europe.