Police officers are being called in by MI5 to openly knock on the doors of suspected extremists whose internet searches or associates have raised concerns, a report has found.

Counter-terrorism officers said use of the new approach to tackle the risks and threats posed by violent extremists has developed over the last two years.

But the report on the effects of the Government’s Prevent strategy, which was launched in 2007 to try to stop people becoming terrorists or supporting terrorism in the UK and overseas, said the more overt and disruption-based methods can never wholly replace covert tactics.

One officer in a “progressive” counter-terrorism unit (CTU) said: “I shan’t name venues, but there’s been a number of occasions where MI5 have been looking at a particular venue for years.

”They’ve done a normal surveillance... and we’re at the point now in this force where we’re being tasked to go into these venues as open CTU officers and say ‘Hello, you know we’re local CTU!’ and we’ve done it and it’s worked.

”Where the service (MI5) have got real concerns about a group of individuals, evidentially they can’t be locked up, let’s just ‘front them’.

”I’ve done a number of those where I knock on the door, ‘Oh can I come in? I’m from the counter-terrorism unit. I’m really concerned about what you’re doing or who you’re hanging around with, what you’re watching on the internet.

”’If you carry on there’s a likelihood you might be arrested, but if you stop, if you want some support or if someone’s trying to get you to do something you’re not happy with, give me a call’.

”I think we’re doing more and more of those and to get to this point from how it was two years ago.

”To have that level of engagement and confidence in what we do from the Security Service is a massive step.”

Last November, Home Secretary Theresa May said the Government would review the Prevent strategy because it was not working as well as it could be.

Today’s report, by Professor Martin Innes of the Universities Police Science Institute in Cardiff, found the initial rush to introduce Prevent “left a toxic endowment”.

”This was recognised by police and communities alike,” he said.

The most effective Prevent policing “integrates defensive and offensive measures”, counteracting specific threats and introducing new tactics and approaches to protect the defenders when individuals and communities ‘push back’ against extremist groups, he said.

The report also found that Britain’s 2.8 million Muslims have a higher level of trust and confidence in the police than the general population.

The evidence does not support the claim that Prevent was causing widespread alienation within Muslim communities because of how it casts them as a “suspect population”, the report said.

”Consistently, across a number of indicators and over time, UK Muslims express similar attitudes to the general population about policing,” it said.

”If anything, their views are more positive.”

While young Muslim men tended to be less positive, 45% of 1,000 surveyed still rated local policing as “good” or “very good”.