Ministers have rejected civil servant advice to widen the definition of extremism to include potentially violent environmentalists, the far left, conspiracy theorists and men prejudiced against women.

It comes after parts of a report – commissioned by the Home Office following the Southport attacks – were leaked to the right-leaning Policy Exchange think tank, which criticised the recommendations.

Home Office minister Dan Jarvis said the government “rejected this advice” adding: “Islamist extremism followed by far-right extremism are the biggest threats we face.”

Asked about the report, Keir Starmer said his government was “looking carefully” at how it addresses extremism.

“It’s very important that we are focused on the threats so we can deploy our resources properly and therefore we’re looking carefully where the key challenges are.”

The prime minister said there was the “additional challenge” in the aftermath of the Southport attacks of “a cohort of loners who are extreme and they need to be factored in”.

The PM added: “In the end, what this comes down to is the safety and security of people across the United Kingdom, that’s my number one focus.”

Home Secretary Yvette Cooper commissioned Home Office officials to conduct a rapid review of the UK’s approach to extremism, in the wake of the last summer’s riots across the UK following the murder of three young girls in Southport.

The review was tasked with shaping a new counter-extremism strategy, addressing online and offline threats from Islamist and the far-right alongside a broader spectrum of extremism.

Leaked sections of the report, published by Policy Exchange, recommend the government’s counter-extremism strategy shift focus to “behaviours of concern” rather than “ideologies”.

Behaviours of concern include violence against women, spreading misinformation and conspiracy theories, fascination with gore or involvement in the online subculture called the “manosphere” – which promotes misogyny and opposition to feminism.

According to Policy Exchange, the report admits many who display such behaviours would not count as extremist.

The think tank has not made public the leaked version of the Home Office report, but published its own assessment which quoted extensively from the document.

The government’s current strategy, known as Contest, is “ideologically agnostic”.

But counter-extremist officers focus most of their efforts tackling Islamism and right-wing extremism – the two most dominant threats to the UK.

MI5 Director Ken McCallum said in October that UK counter-terror efforts deal 75% with Islamist threats and 25% with far-right extremists.

The report urges expanding extremism’s definition to cover, alongside Islamists and extreme right-wing:

• extreme misogyny,
• pro-Khalistan extremism, advocating for an independent Sikh state
• Hindu nationalist extremism,
• environmental extremism,
• left-wing, anarchist and single-issue extremism (LASI),
• violence fascination and,
• conspiracy theories

The Home Office review found claims of two-tier policing, where two groups are allegedly treated differently after similar behaviour, were a right-wing extremist narrative leaking into mainstream debates.

Government sources have strongly criticised the report and said certain elements of it were shocking, despite it having been conducted by the Home Office’s own officials.

However, the government will need to work out a way, whether based on the report or not, to deal with violent individuals and ideologies.

The BBC has not seen a full copy of the report.

Southport killer Axel Rudakubana was last week sentenced to a minimum of 52 years jail for the “sadistic” murders of three young girls.

In response, Prime Minister Sir Keir Starmer said terrorism “has changed” in Britain and a review would be carried out into “our entire counter-extremist system”.

While in the past he said the “the predominant threat was highly organised groups with clear political intent”, alongside that there were now also “acts of extreme violence perpetrated by loners, misfits, young men in their bedroom”.

Danny Shaw, a former adviser to Cooper, told the BBC’s Today programme he had seen a summary of the report and backed one of the recommendations which said “the counter-extremism function should take an approach based on behaviours that cause harm rather than one based on definition”.

“That approach was not taken in the case of Axel Rudakubana because he didn’t fit a definition that meant he could have intervention by Prevent so he was transferred away and passed from one agency to another,” he added.

He said the focus should be on the “behaviour that causes most harm – whether it’s got an ideology or not”.

Appearing on the same programme, Nick Aldworth, a former detective chief superintendent in counter terrorism, expressed concern about police resources, adding: “If you have a definition or legislation that can’t easily be policed it is probably not worth doing.”

The Policy Exchange authors, who released the Home Office findings, said the review “runs in the wrong direction”.

Former journalist and government advisor Andrew Gilligan and Paul Stott, the head of security and extremism at Policy Exchange, said: “The purpose of counter-extremism and counter-terrorism is to defend the security of the country, its democratic values and institutions against those whose beliefs and acts intentionally threaten them.

“Such threats come overwhelmingly from those with an ideological or political motive, principally Islamism but also far-right and other forms of extremism.”

The report’s recommendations “risk swamping already stretched” security services, while redefining extremism “threatens free speech,” the authors said.

Shadow home secretary Chris Philp said: “By extending the definition of extremism so widely, the government risks losing focus on ideologically motivated terrorists who pose the most risk to life.”

He added: “Other appalling and unacceptable criminal behaviour that is not ideologically motivated – of which there are many kinds – should be dealt with via the police and criminal justice system, and via other agencies such as social services and mental health services, including sectioning those that present a risk.”

Additional reporting by Sam Francis.