POLICE undercover operations and covert tactics are to be reviewed in the wake of the Pc Mark Kennedy case.
Her Majesty's Inspectorate of Constabulary (HMIC) has launched the inquiry following concerns about the role played by the ex-Metropolitan Police officer, who spent seven years undercover posing as an environmental activist.
The tactics used during the operation have been questioned after it was exposed when a court case collapsed.
Six protesters accused of planning to invade Ratcliffe-on-Soar power station in Nottinghamshire claimed charges were dropped after Mr Kennedy offered to give evidence on their behalf.
The former officer has denied accusations he "went rogue" and said he reported to his unit every day. The 41-year-old said he fears for his life and described the world of undercover policing as "grey and murky", adding: "There is some bad stuff going on. Really bad stuff."
The review will take into account separate inquiries by the police watchdog the Independent Police Complaints Commission (IPCC), and Scotland Yard, HMIC said.
Policing Minister Nick Herbert said: "It's clear to us all that something operationally has gone very wrong and that is now the subject of an Independent Police Complaints Commission investigation.
"I think everybody is concerned by the Kennedy case and we have an IPCC precisely to investigate this kind of thing."
Concerns over the operational accountability of Mr Kennedy's unit, the National Public Order Intelligence Unit (NPOIU), were raised by MPs on the Commons Home Affairs Select Committee.
Mr Herbert said there needed to be "proper accountability" for the Association of Chief Police Officers (Acpo), which is running the unit until it can be transferred to Scotland Yard.
Keith Vaz, chairman of the Commons Home Affairs Committee, will also write to Acpo president Sir Hugh Orde over concerns that Mr Kennedy was given a 200,000 per year expenses account while working undercover.