British police are to pay compensation to woman who had a child with a man she did not know was an undercover agent, the Guardian and BBC reported on Thursday.

The 425,000 pounds ($681,000, 539,000 euros) payment follows a legal battle by several women who say they were tricked into having relationships with officers sent to spy on political activists.

Known only as "Jacqui", the woman said she had received psychiatric treatment since discovering the true identity of her child's father in a newspaper in 2012.

"He presented himself as Bob Robinson, a long-haired leftwing radical," the woman known as "Jacqui" told the Guardian.

"In reality he was a member of a secret police unit, the special demonstration squad, and was embarking on a five-year mission to infiltrate environmental and animal rights groups."

The man disappeared from her life when the child was two years old, going back to his original wife, children and identity.

Now an academic, he was one of several officers who had undercover roles as part of the now-defunct special demonstration squad between 1968 and 2008.

He was confronted in 2012 at a conference by members of London Greenpeace, who said he had infiltrated their group in the 1980s as it campaigned on nuclear and environment issues.

Police later acknowledged that he had been an undercover officer.

A Scotland Yard spokesman said the force "unreservedly apologises for any pain and suffering that the relationship" caused.

However, it added that it "never had a policy that officers can use sexual relations for the purposes of policing".

In August, four former officers in the squad were told they would not face criminal charges for forming sexual relationships with women while undercover.

Several other legal claims relating to undercover officers are ongoing.