LONDON (AP) — British security forces have thwarted 13 terrorist attacks in less than four years, mostly thanks to information provided by the public, the country's most senior anti-terrorism official said Monday.
Mark Rowley, assistant commission for London's Metropolitan Police, said security and intelligence agencies are dealing with more than 500 investigations at any one time.
The terrorism threat to Britain is categorized as "severe" — meaning an attack is "highly likely" — as authorities faced "some big operational challenges," Rowley said in an interview with local media.
He said military success against the Islamic State group in Iraq and Syria is "welcome" though that alone is "not going to eradicate the terrorist problem." Al-Qaida and off-shoots of both groups remained a threat, he said, but "extreme right-wing groups" have also become a focus of police efforts in recent months.
The number of people leaving Britain to fight with extreme Islamist groups has fallen, he said. Up to 800 people are believed to have left Britain to fight in Syria and Iraq. It is not known exactly how many have returned home, though some experts say it could be up to half, with some 50 killed.
"The majority (of our work) is actually people in this country who are radicalized," Rowley said. "Sometimes they are in contact with people overseas and they are looking to radicalize others in this country and potentially conduct attacks."
The attention on home-grown far-right extremism follows the killing of lawmaker Jo Cox last June, ahead of the Brexit referendum on Britain's European Union membership.
The country's last Islamist terrorist attack was in May 2013, when British Army soldier Lee Rigby was killed by two British converts to Islam who were known to security services for their extremist views.