The “febrile” atmosphere around Brexit could be exploited by far-right extremists, the UK’s most senior counter-terrorism officer has warned.
Assistant Commissioner Neil Basu said 18 terror plots were foiled in Britain since 2017, four of them far-right.
He said a “far-right drift into extreme right-wing terrorism” was a concern but officers were working to ensure groups did not gain a “foothold”.
Mr Basu added leaving the EU with no deal would be “very bad” for policing.
The head of the Metropolitan Police’s counter-terrorism operations was speaking at the launch of a new cinema advert aimed at encouraging people to report their suspicions about all forms of terrorism.
The 60-second film portrays a series of scenarios, including a man stockpiling hazardous material and another buying weapons.
Mr Basu revealed that a record 700 terror investigations are currently taking place, up from about 500 in March 2017.
Fourteen of the attacks foiled since 2017 involved Islamist suspects, Mr Basu said, adding that he was concerned about the possibility of radicalised fighters returning from abroad.
Another concern was the spread of propaganda online.
Mr Basu said while extreme right-wing activity was still a “relatively small threat”, it was also “something we’ve got to pay very close attention to in this country – that we don’t let that kind of far-right drift into extreme right-wing terrorism and we’re working very hard to stop that”.
Asked about the background of Brexit, Mr Basu told the BBC: “We saw a spike in hate crime after the referendum, that’s never really receded.
“So there’s always a possibility people are being radicalised by the kind of febrile atmosphere we’ve got at the moment.
“We want people to report anything that we think is going to lead to violent confrontation and people need to calm down and understand that we are paying very close attention to that and we will stop it wherever we see it.”