The Independent Police Complaints Commission (IPCC) has announced an inquiry into leaks about the police shooting of Jean Charles de Menezes.
After the leak, Mr Menezes' family called for Sir Ian Blair to resign
The Brazilian, 27, died at Stockwell Tube station on 22 July after officers mistook him for a suicide bomber.
Details of the IPCC inquiry into the shooting were leaked to the media on 16 August and led to claims of a cover-up.
Former Chief Inspector of Constabulary for Scotland Bill Taylor will lead the independent inquiry into the leak.
The information contradicted much of what had previously been thought about Mr Menezes' death and led his family to demand the resignation of Metropolitan Police chief Sir Ian Blair.
The IPCC's announcement of an inquiry is the first time it has conceded that the leak came from its offices.
The commission said Mr Taylor would "lead the inquiry into the leak of unauthorised material from the IPCC that was reported in the media on 16 August and on the following days".
"He will make recommendations relating to any individuals involved and what steps the IPCC could take to reduce the risk of such unauthorised disclosure in future," it said.
Mr Taylor will report to IPCC chairman Nick Hardwick. His findings will be published.
The Metropolitan Police and Police Federation had earlier demanded that the home secretary launch an independent inquiry into the leak.
Glen Smyth, chairman of the Met Police Federation, said it had written to Charles Clarke because it saw "no value in writing to the IPCC about the conduct of its own people".
He said: "It does not seem able to police itself - if we thought it could we would not be writing to the home secretary."
The Police Federation also wrote to the IPCC to say the leaks called into question its ability to conduct inquiries in a "professional and independent manner".
Police Federation vice chairman Alan Gordon welcomed the announcement, saying that the incident had undermined confidence between police and the IPCC.
"We need to re-build that as quickly as possible, because it's vital that police officers as well as the public have confidence in an independent complaints commission that will effectively look at complaints that are made against the police," he said.
"But they have to act in an impartial way. That confidence has been rocked, this inquiry will hopefully re-build it," Mr Gordon added.