The official scheme to stop people becoming terrorists risks being damaged by scandals such as listing Extinction Rebellion as an extremist ideology, a former senior police chief has said.

Sir Peter Fahy, who was head of Prevent from 2010 to 2015, said confidence from communities was vital to its success and legitimacy.

He was speaking after the Guardian revealed police had branded the nonviolent climate emergency group as an extremist ideology in a guide designed to help stop terrorist violence.

The publication produced by counter-terrorism police in the south-east showed police had placed XR on a list of ideologies alongside neo-Nazis and Islamist extremists that should be reported to the authorities running the Prevent anti-radicalisation programme.

Fahy, a former chief constable of Greater Manchester police, said: “Prevent is about stopping terrorist acts against people or property and XR is not in that territory at all.

“XR is about lawful protest and disruption to get publicity – it is very different from terrorist acts.”

The guide was sent to police officers, teachers and others in government. Police said they had since recalled the document and that including XR was an error.

Quick Guide What is Prevent? Show What is Prevent? Prevent is one of the four “Ps” of the government’s counter-terrorism strategy, along with Pursue, Protect and Prepare. It was created by the Labour government in 2003 and its remit was widened by the coalition government in 2011. Its stated purpose is to safeguard and support those vulnerable to radicalisation and to stop them from becoming terrorists or supporting terrorism. How does it prevent people from becoming terrorists? Individuals suspected of being vulnerable to radicalisation can be referred to police for further assessment. One of the most controversial aspects of Prevent was the statutory duty introduced in 2015 on schools, NHS trusts, prisons and local authorities to report concerns about people who may be at risk of turning to extremism or terrorism. Once referred, the individual will be assessed to see whether or not further intervention is required. If an individual is assessed to be vulnerable to radicalisation, they may be offered support through the Channel programme in England and Wales, or the Prevent Professional Concerns (PPC) programme in Scotland. This is a voluntary process. Between 2017 and 2018, a total of 7,318 individuals were subject to a referral but only 394 were escalated to the Channel process. Why is Prevent controversial? The most common criticism levelled at the Prevent strategy is that it disproportionately impacts people of Muslim faith or background and inhibits legitimate expression. There have been numerous reports over the last 15 years that have fuelled this perception: an eight-year-old questioned by Prevent after his teachers mistook his T-shirt slogan for Islamic State propaganda, a 17-year-old referred because he wore a “Free Palestine” badge to school and a student of counter-terrorism questioned after an official spotted him reading a textbook entitled Terrorism Studies. The Prevent brand has been labelled “toxic” in parts of the Muslim community. But senior policing and security figures continue to back Prevent. In September 2019 the UK’s most senior counter-terrorism officer, Neil Basu, vigorously defended the programme in a speech in Israel, while security ministers and former home secretaries have insisted it has saved lives. Jamie Grierson, Home affairs correspondent

Fahy said confidence in Prevent was crucial to its success in stopping the flow of terrorists, and risked being damaged by the inclusion of the nonviolent group in the guide. ”It is clearly disappointing,” he said. “Prevent has to be about safeguarding people from becoming involved in terrorism.

“Prevent does depend on having the confidence of communities, and for instance of teachers because you need them to have confidence they can feed in information and it will be used proportionately. Unfortunately, this does risk damaging confidence in Prevent.“

Lawyers for XR will write to police on Monday demanding the guide is withdrawn, not just recalled, and asking for details about whether anyone was referred to Prevent as a result of it being issued.

Tobias Garnett, from XR’s legal strategy team, said: “Our lawyers are requesting that this guidance be formally withdrawn and any referrals of individuals to Prevent reversed.

“It is patently absurd to put a nonviolent movement of people urging the government to take action on the climate and ecological emergency on a list of extremist ideologies. This is not extremism, it is level-headedness in the face of scientific consensus and fires that now rage from Australia to the Amazon.”

The challenge to the authorities from XR comes from its campaigns of civil disobedience and its popularity among the young. The Guardian revealed in October that police and government were in talks to acquire tougher powers against XR.

One senior police source said police were under pressure from the government, which was annoyed by the disruption such protests cause, and said ministers and officials wanted to see more robust and proactive action.

“They want ‘move forward’ tactics and to see the police are doing something and clearing the streets. Government wants police to be more robust earlier and more often,” the source said.

A Metropolitan police ban on XR protests was ruled unlawful last year.

In July a pamphlet by the rightwing thinktank Policy Exchange, which has been influential in Conservative party thinking and policy, branded XR as extreme and called for a tougher crackdown on its protests. Both of the thinktank’s key demands did, to some extent, happen.

It was co-authored by a former Scotland Yard counter-terrorism chief, Richard Walton, and ended its 70-page attack by saying: “To date, there has been a marked failure to call out this extremist agenda for what it is.”