Scotland Yard has apologised to seven women who were deceived into "abusive, deceitful, manipulative and wrong" relationships with undercover police officers.
The Metropolitan Police said it has reached a settlement with the women over civil claims relating to the "totally unacceptable" behaviour of a number of officers working for two now disbanded units.
Assistant Commissioner Martin Hewit said: "I acknowledge that these relationships were a violation of the women's human rights, an abuse of police power and caused significant trauma.
"I unreservedly apologise on behalf of the Metropolitan Police Service. I am aware that money alone cannot compensate the loss of time, their hurt or the feelings of abuse caused by these relationships."
The unprecedented apology and payouts centre on the conduct of officers working for the Special Demonstration Squad (SDS), an undercover unit within Special Branch that existed until 2008, and for the National Public Order Intelligence Unit (NPOIU), which was operational until 2011.
The details of the settlement are being kept secret.
Mr Hewitt said: "Thanks in large part to the courage and tenacity of these women in bringing these matters to light it has become apparent that some officers, acting undercover whilst seeking to infiltrate protest groups, entered into long-term intimate sexual relationships with women which were abusive, deceitful, manipulative and wrong."
The senior officer heard directly from the women involved during a mediation process.
He said: "I wish to make a number of matters absolutely clear.
"Most importantly, relationships like these should never have happened. They were wrong and were a gross violation of personal dignity and integrity."
In his statement, Mr Hewitt said:
:: None of the women with whom the officers had a relationship "brought it on themselves", adding: "They were deceived pure and simple."
::The women's privacy had been "grossly violated".
:: It is apparent that some officers may have "preyed on women's good nature" and "had manipulated their emotions to a gratuitous extent".
:: That the relationships and the subsequent trauma left the women "at risk of further abuse and deception by these officers after the deployment had ended".
:: Whether or not genuine feelings were involved on the part of any officers is "entirely irrelevant and does not make the conduct acceptable".
The assistant commissioner added that the relationships may well have reflected attitudes towards women that "should have no part in the culture of the Metropolitan Police".