The UK has not “woken up” to the threat posed by the far right, the former head of the Metropolitan police’s counter-terrorism unit has said.

Mark Rowley urged politicians, the media and communities not to underestimate the threat of far-right groups, citing how National Action, a proscribed neo-Nazi organisation, has “a strategy for a terrorist group” with online materials advising on how to sow tension and discord in communities and evade police surveillance.

“For the first time since the second world war we have a domestic terrorist group, it’s rightwing, it’s neo-Nazi, it’s proudly white supremacist, portraying a violent and wicked ideology,” Rowley told BBC Newsnight.

“If we sleepwalk into it, then I think there is a real danger we give them more scope to get stronger. They’re repackaging their aggressive intolerance and sometimes thinly disguised advocation of violence, they’re repackaging that and attaching it to mainstream political debate.”

Rowley, who was the Met’s anti-terrorism chief between 2014 and 2018, said the UK needed to be alert and ensure extremist groups could not “generate credibility and present themselves as representatives of white Britain or Muslim Britain”.

National Action became the first far-right group to be banned under terrorism laws in December 2016 and it is now a criminal offence to be a member of the group.

The group celebrated the murder of Labour MP Jo Cox in 2016, and this summer one of its alleged pre-ban members pleaded guilty to a plot to murder another Labour MP, Rosie Cooper.

Nick Lowles, founder of the anti-racist and anti-fascist campaign group Hope Not Hate, said: “While Mark Rowley is right in saying that neo-Nazi ideas have not gone mainstream, what is abundantly clear is that an anti-immigrant, and particularly an anti-Muslim narrative, increasingly dominates the mainstream media and this can lead people into the hands of far-right extremists.” Rowley referenced four far-right plots that were foiled last year and claimed there has been a lack of recognition of the threat posed.

“I don’t think we’ve woken up to it enough,” he said. “Now I’m not going to say that it’s the same level of threat as the Islamist threat. From last year’s numbers for example, out of 14 plots stopped, 10 were Islamist, four were extreme rightwing, so no pretence that it’s exactly the same order of magnitude, but it’s very significant and growing, and what I’ve seen over the last couple of years is a lack of recognition of that.”

There were 676 open counter-terrorism investigations across the UK that involved more than 3,000 subjects of interest according to the latest figures up until June, Downing Street recently revealed.