WELSH activists are bringing a landmark case against the police over its blanket “neither confirm nor deny” policy towards undercover officers.

Police have maintained a stony silence in the face of mounting allegations about the conduct of undercover officers, refusing to say whether alleged miscreants even worked undercover.

But three south Wales anarchists — two women and a man — will be at the Royal Courts of Justice next week trying to strike down that defence.

They’re taking the Met, South Wales Police and the Association of Chief Police Officers to court over Mark “Marco” Jacobs’s actions over five years in Brighton and Cardiff up to 2009.

During this time Mr Jacobs developed a number of close personal relationships and, in common with several other undercover police who have been exposed, engaged in sexual relationships with a number of his targets.

One of the claimants, Tom Fowler, told the Star that he’d first met Mr Jacobs at protests before the spook moved to Cardiff and got involved with local anarchist groups.

“He became what I thought was a close personal friend. He totally infiltrated people’s lives.”

It was only when Mr Jacobs suddenly disappeared in 2009, saying he was moving to Corfu, that people began to get concerned.

When former undercover officer Peter Francis went public in 2010, Mr Fowler realised that his story was almost identical to that of Jacobs.

Mr Jacobs had presented himself as a caring friend and had been with Mr Fowler through a number of personal traumas. The betrayal was “devastating,” he said.

Mr Fowler said he does not expect justice from the courts but hopes that by showing what happened he can highlight the issue and set a legal precedent to allow others to bring similar action.

The case will be heard at the Royal Courts of Justice on March 25, with a solidarity picket at 9am.

The evening before, activists will protest outside Cardiff Central police station from 6-8pm to draw attention to the case.