Undercover police officer Mark Kennedy 'defied' bosses
An undercover policeman whose actions led to the collapse of a trial of environmental protesters had "defied" management instructions, a report says.
HM Inspectorate of Constabulary reviewed the activities of Mark Kennedy and other undercover officers.
The inspectorate found that Mr Kennedy, who infiltrated environmental groups, helped unearth "serious criminality".
But it said he was inadequately supervised and oversight of undercover officers needed to be strengthened.
Code of conduct
The inspectorate suggested that an independent body may be required to authorise deployments.
The review was set up after the case sparked wider concerns about the deployment of undercover officers by the National Public Order Intelligence Unit.
The report said that during his seven years undercover Mr Kennedy had become "resistant to management intervention" and carried on working "contrary to instructions" after being arrested in 2006.
The inspectorate said Mr Kennedy operated outside the code of conduct for undercover officers - he claimed to have had at least two relationships with female protesters.
Such behaviour is not explicitly banned under the code but is considered to be "grossly unprofessional".
The review made four recommendations for more robust controls of undercover police work.
These include greater oversight by the Office of Surveillance Commissioners, and a thorough review of all operations that last more than six months.
In December, a report by retired judge Sir Christopher Rose concluded that failures by police and prosecutors led to the collapse of the trial.
The case failed when it emerged that Mr Kennedy had infiltrated and potentially entrapped environmental activists. A further 20 activists had their convictions quashed on appeal following the officer's unmasking.
Mr Kennedy spent years underground, infiltrating green groups involved in high-profile climate change protests.
In 2009, Nottinghamshire Police arrested more than 100 people from a group that Mr Kennedy had infiltrated. Twenty of them were convicted in December 2010 of plotting to shut down the coal-powered Ratcliffe-on-Soar power station near Nottingham.
But a second proposed trial of six more protesters collapsed in January 2011 after it emerged that the officer wanted to use his secret recordings to help the defence.
The collapse of the trial led the Court of Appeal to quash the convictions of the first 20 protesters - but also triggered inquiries into the affair and the role of undercover police officers.