A major review of criminal convictions in cases involving undercover police officers has been launched in a bid to flag up potential miscarriages of justice.
Home Secretary Theresa May said the review will look at whether convictions are safe in cases where undercover activity was not revealed to the prosecutor and therefore not considered by the court.
If the review, which will be led by Mark Ellison QC, who previously carried out the Stephen Lawrence Independent Review, identifies a potential miscarriage of justice, the case may be referred to the Criminal Cases Review Commission for consideration over whether it should be referred to the appeal courts.
The Home Secretary said: " Undercover police operations are vital in the fight against crime.
"But we expect the highest standards of professionalism in all aspects of policing. If allegations of wrongdoing are made, it is important they are investigated thoroughly.
"Where Mark Ellison's review identifies a potential miscarriage of justice, the case may be referred to the Criminal Cases Review Commission for consideration whether it should be referred to the appeal courts."
The review comes in the wake of findings of Mr Ellison's probe into the handling of the Stephen Lawrence investigation.
Police moles fell under the glare of the inquiry after former SDS officer Peter Francis claimed he had been deployed undercover from September 1993 and tasked to ''smear'' the Lawrence family campaign.
Mr Ellison found that an SDS "spy" was working within the "Lawrence family camp" during the judicial inquiry led by Sir William Macpherson into Stephen's death in the late 1990s.
The review will initially focus on the undercover police activity of the Metropolitan Police's Special Demonstration Squad (SDS).
It will also look at the actions of the National Public Order Intelligence Unit which, while not part of the Met, worked to similar objectives.
The terms of the review include i dentifying how many police, prosecution and court case files still survive, as well as finding out what sort of undercover policing was carried out and the potential for this activity to have been relevant to a prosecution but kept secret.
The review will also seek to i dentify any convictions which might be unsafe due to unrevealed undercover police activity, as well as ensuring these cases are referred to the relevant authority to be evaluated and action taken.
Earlier this year, Mrs May also announced a judge-led public inquiry into the work of covert police and Scotland Yard's Special Demonstration Squad (SDS) - the top secret unit that was up and running for nearly 40 years.
Shami Chakrabarti, director of human rights campaign group Liberty, said: " So much for 'nothing to hide, nothing to fear'.
"Magistrates' warrants are needed to search homes and the Home Secretary's approval required to tap phones - why then are police allowed to put spies in the heart of families for years without proper oversight?
"Only prior judicial authorisation and continuing review will clean up the dark, corrupting practices of undercover policing."