Successive prime minsters knew about the existence of an undercover Metropolitan Police unit which spied on left-wing activists, campaigners have said.

The Undercover Policing Inquiry into the unit's activities will hear closing submissions in the first stage or Tranche One of its evidence, which looks at practices in the Special Demonstration Squad between 1968 and 1982, early next week.

The inquiry has been told women's groups, political parties, unions, teachers and students were monitored by undercover officers engaged in “political policing” that targeted those perceived to be left-wing.

It has also heard sexual activity between undercover police officers and members of the public who did not know their true identities was “not uncommon” from the mid-1970s.

One woman is said to have been tricked into a relationship with an undercover officer until 2015.

An online press conference held by campaigners on Friday was told civil servants, the Home Office, Cabinet Office and prime ministers were aware of the spying.

Lawyer Lydia Dagostino, who is the co-ordinator for the campaigners legal representatives, said: “Successive prime ministers knew of this unit.

“It was approved and funded with the knowledge of our senior politicians and civil servants, and was a tool by the state to spy on the left and anyone deemed subversive.”

Trade unionist Dave Smith of the Blacklist Support Group claimed the information supplied was sold to “major employers” including the NHS, Post Office, BBC, civil service and British Steel.

He claimed former prime minister Edward Heath was “aware of this information” and had used it in discussions with senior civil servants.

He said requests were made about “vetting” which “is a euphemism for blacklisting”.

He added: “What has been disclosed in Tranche One is Cabinet Office papers that have explained that at PM level Edward Heath was aware of this information-sharing between major employers.

“Some of this information has been disclosed by the public inquiry and some of it hasn't. Information is already in the National Archives.

“There were Labour governments this was going on under and we have no doubt Tony Blair, Gordon Brown and other Labour PMs were given it as well.”

He also claimed at one point “concerns” were raised about the attitude of an incoming Labour prime minister to the unit which eventually proved unfounded.

One woman who had a relationship with an undercover officer, who referred to herself as Alison, called the unit “instinctively sexist and racist” and said a direct line can be traced from the undercover policing scandal to current ones affecting the Met.

The woman, who is a campaigner for the Police Spies Out of Lives group, said undercover officers talked about sexual “conquests”, made racist remarks about a Jewish campaigner's nose, one had a sex with four women and another had “a couple of relationships” with women while undercover.

She said: “The deployments were unlawful and unjustified, these officers trespassed into our homes, women were considered to be commodities to be exploited.

“We didn't consent to have intimate sexual relationships with undercover police and the police knew this.

“One woman was asked whether she would have slept with someone she knew to be an undercover police officer and she replied ‘no.'

“A culture of misogyny was clearly established in the 1970s and 1980s.

“Today we are seeing the consequences of this misogynistic culture in some of the appalling scandals recently.

“We are frustrated, angry and disturbed as are most people.”

Former prime minister Theresa May established the inquiry in 2015 when she was still Home Secretary after independent reviews by Mark Ellison KC found “appalling practices in undercover policing”.

A public outcry was sparked when it was revealed that women had been tricked into sexual relationships with undercover officers and that police spies had used the identities of dead children without their families' permission.

The inquiry dealt with preliminary issues for five years until 2020 and is due to conclude in 2026.

Mr Smith claimed that while the unit and its successor, which existed into the 21st century, have been closed down, the activity is “still going on.”

He added:: “We have exposed it, what they have done is move the goalposts to make what they have done perfectly legal.”