There were "serious weaknesses" in the Metropolitan Police's handling of information after the shooting of Jean Charles de Menezes, a report has found.
Jean Charles de Menezes was shot eight times
Assistant Commissioner Andy Hayman "misled" the public, the Independent Police Complaints Commission ruled.
The IPCC has examined statements issued by police after the 27-year-old was mistakenly shot dead by officers at Stockwell Tube station on 22 July 2005.
Met Commissioner Sir Ian Blair said Mr Hayman "retains my full support".
Mr Menezes was shot dead after police launched a massive manhunt for four suspects following a series of attempted bombings across London's transport network. The Brazilian was mistaken for a suicide bomber.
After the shooting, there were reports about Mr Menezes in the media which turned out not to be true - such as that he was wearing a bulky jacket - and the IPCC considered whether the Met was responsible.
The report highlighted inconsistencies between what Mr Hayman had told a crime reporters' briefing and a Metropolitan police authority management meeting on the day of the shooting.
It said Mr Hayman - the UK's most senior counter terrorist-officer - had advised the reporters that the dead man had not been one of four attempted bombers.
However, he had also allowed a Metropolitan Police press release to be issued later on the same afternoon, saying that it had not been clear whether he had been one of the four.
"He could not have believed both inconsistent statements were true," the IPCC said.
Sir Ian did not announce that an innocent man had been killed until the following morning, but a complaint against the commissioner was not substantiated.
IPCC Commissioner Naseem Malik told a news conference information had been "deliberately withheld" from Sir Ian.
She said: "What the commissioner could, and should, have been told was the emergence of evidence throughout the day that pointed increasingly strongly to a terrible mistake having been made."
Sir Ian later said officers did not inform him on 22 July that an innocent man had been shot, because of the time it took to establish that Mr Menezes's identity was not an alias.
He added: "I neither believe that my senior colleagues let me down nor that my position on that night was unreasonable."
Sir Ian said he could not comment on the allegations against Mr Hayman, but said he retained his support in a "crucially important job".
In a statement, the Metropolitan Police apologised for "errors in both internal and external communication".
It said its approach to information-handling had changed since 2005.
The Met had "previously apologised to the de Menezes family for their loss and we apologise again", it added.
BBC home affairs correspondent Andy Tighe said the ball had now entered the court of the Metropolitan Police Authority, which will decide whether Mr Hayman should be disciplined.
After the IPCC's Stockwell One report into the events surrounding the shooting, the Crown Prosecution Service decided last year that no individual would be prosecuted in connection with the case.
However, the Metropolitan Police is facing trial under health and safety legislation in October.
Allesandro Pareira, a cousin of Mr Menezes, told a press conference through an interpreter that "this report shows that the police were a shambolic mess and that senior officers lied".
Liberal Democrat party president Simon Hughes said Mr Hayman should resign, but London Mayor Ken Livingstone earlier gave the officer his backing.