A band of undercover police officers accused of sleeping with women they were spying on have been told they face no criminal charges for their actions.
Four Scotland Yard officers from the enigmatic and now-defunct Special Demonstration Squad (SDS) were being investigated for offences including rape and indecent assault.
Covert police from the mysterious unit, which was ran between 1968 and 2008, have faced a number of startling claims of rogue behaviour including fathering children with women they spied on after infiltrating environmental campaign groups and forming long-term relationships with them.
While a civil suit brought by eight women continues in the High Court, the Crown Prosecution Service (CPS) said there was not enough evidence to charge four officers with sexual misconduct offences.
Solicitors representing the women suing the Metropolitan Police said they were dismayed by the decision and one of their clients, who first provided a statement to the police three years ago, was considering challenging the CPS decision.
A statement from Birnberg Peirce and Partners said the women had reacted "with dismay" to the CPS announcement that " no criminal charges will be brought against any officers who operated within the Metropolitan Police Special Demonstration Squad".
Scotland Yard said it was now considering if misconduct proceedings were appropriate for the four officers.
The Met was forced to name two officers who allegedly had relationships with women activists in groups they infiltrated after High Court judge Mr Justice Bean ruled the force could not use its policy of ''neither confirm nor deny'' (NCND) in response to the damages claims.
As a result, the force confirmed Jim Boyling and Bob Lambert were undercover police officers.
John Dines, Mark Cassidy and Mark Kennedy have also previously been named as their colleagues.
The women are claiming for deceit, assault, negligence and misfeasance in public office arising out of long-term and intimate sexual relationships they had with four men who - unknown to them - were members of the SDS, between 1987 and 2007.
Birnberg Peirce added: "One woman known as 'Laura' who provided a detailed statement to the police over three years ago about her relationship with Jim Boyling and his deception and abusive behaviour, has said she is considering seeking a review of the CPS decision."
The claims were being investigated as part of Operation Herne, an investigation into the activities of the SDS, including using dead children's identities.
Within that probe, prosecutors considered a file relating to Operation Aubusson, looking at alleged sexual misconduct by the officers.
The CPS said it had considered whether there was sufficient evidence to allow charges of rape, indecent assault, procuring a woman to have sexual intercourse by false pretences, misconduct in public office and breaches of the Official Secrets Act.
In a statement it said: " Having carefully considered all the available evidence, provided at the end of a thorough investigation, we have determined that there is insufficient evidence for a realistic prospect of conviction for any offences against any of the officers.
"Investigators from Operation Aubusson have confirmed that no further lines of enquiry are available at this time.
"The suggestion has been made publicly that officers, while allegedly acting undercover, may have committed sexual offences in relation to personal relationships they formed during their deployment.
"There was only one complaint of criminal activity against one of the officers, but a number of other officers were considered as a result of allegations made publicly which investigators had become aware of."
A raft of allegations were made after former Pc Mark Kennedy was unmasked in 2011 as an undercover officer who spied on environmental protesters as long-haired drop-out Mark ''Flash'' Stone.
It has been claimed that five undercover officers engaged in infiltrating environmental campaign groups between the mid-1980s and 2010 had relationships with the women, lasting from seven months to nine years.
A Scotland Yard spokesman said the force had been informed by the CPS that no police officer would face any charges in connection with one strand of Operation Herne.
Last year, College of Policing chief executive Alex Marshall told MPs that a new code of ethics for officers would ban u ndercover police from having sex with individuals they spied on.
London Assembly Green Party Member Jenny Jones, who has campaigned in support of the women suing the Met, said: " The CPS has looked at the evidence put together by the police investigating the police and decided not to charge any undercover police officer.
"I find this decision by the CPS quite staggering and it will damage trust in both the CPS and the police.
"The CPS appears not to have looked at the use of sexual relationships as a systematic tactic used by a group of undercover officers during their deployment and that concerns me.
"We have heard time and again from senior officers that such relationships are completely unacceptable and yet today's decision by the CPS means these officers have escaped being held to account.
"One of the victims of these officers said she felt as if she had been 'raped by the state'.
"Unfortunately, today's decision by the CPS means she, and the other victims of undercover police, will be denied justice.
"I hope the CPS will reconsider its decision and puts these cases before a jury.
"I urge the Mayor of London to lobby the DPP."