The numbers arrested in Europe on suspicion of jihadist activities nearly doubled over the last two years, Europe's policing agency said Thursday, with an alarming rise among women and young adults.
Some 718 suspects were arrested on offences relating to jihadist terror last year as opposed to 395 in 2014, Europol said in its annual EU Terrorism Situation and Trend Report.
But actual attacks dropped from 17 in 2014 to 13 last year -- of which six were linked to the Islamic State group.
The 62-page report also pointed out that women and children, as well as young adults played an increasingly important operational role.
"Female militant jihadists in the West perceive fewer obstacles to playing an operative role in a terrorist attack than men, and successful or prevented attacks carried out by women in western countries may act as an inspiration to others," it noted.
One in four of those arrested in Britain in 2016 were women, an 18 percent increase from 2015, Europol said.
In France -- the EU country with the highest number of arrests at 456 last year -- almost a third of the suspects were 25 years or younger, Europol said.
Overall there were 142 "failed, foiled or completed terrorist attacks" including those by jihadists -- with more than half in Britain.
Britain was rocked by a suicide bombing at a pop concert in Manchester on May 22 which killed 22 people, including children. Two weeks later, a knife and van attack in central London left eight dead.
Of the 142 victims of terror attacks last year, 135 died in jihadist attacks, said the report.
That reinforced the need for closer cooperation in intelligence sharing among member states, security officials urged.
"Terrorists do not respect or recognise borders," said EU safety chief Julian King.
"In our resolve to defeat them we must draw on a new-found determination to work together, sharing information and expertise," he said in the report.
But the report also noted that not all attacks were jihadist-inspired. Most of the other attacks were carried out by "ethno-nationalist" and separatists extremists.
For instance "dissident Republican groups in Northern Ireland were involved in 76 attacks," the report said, leading to a total of 123 arrests.
British authorities in May last year raised the threat level because of terror-related incidents in Northern Ireland from "moderate" to "substantial".
This "means an attack is a strong possibility," Europol said.
In total 1,002 arrests overall were made in 2016 relating to terror activities.