Two senior officers, one a counter-terrorism expert, have given testimony that appears to contradict Blair’s claims.

They have given signed statements to the Independent Police Complaints Commission (IPCC) that just hours after Jean Charles de Menezes was killed on July 22 they were told there was a “possibility” that an innocent man had been killed.

The officers say they were instructed to carry out an assessment to help handle the expected public relations backlash to the bungled shooting.

One of the new witnesses is Robert Beckley, an assistant chief constable of Hertfordshire police, who was visiting the Yard that afternoon for a previously planned meeting to discuss terrorism.

Beckley is a senior member of the terrorism committee of the Association of Chief Police Officers and is chairman the association’s committee on relations with the Muslim community. He also commands a national intelligence unit that monitors tension within ethnic communities.

Well-placed police sources say Beckley was at the meeting about six hours after the shooting when a more senior officer told him the wrong man may have been killed.

One officer said: “[The conversation] was around the possibility that there had been a mistake and they had to plan around it”.

Beckley has told the IPCC that he and another officer were immediately asked to start drawing up an analysis of how the Met’s relations with the ethnic minority community would be affected if the wrong person had been shot.

Beckley’s evidence is said to be supported by a second officer, a commander in the Met, who was also present at the meeting and has given a signed statement to the IPCC.

One month after the killing, Blair said: “The key component was that at the time — and for the next 24 hours — I and everybody who advised me believed the person who was shot was a suicide bomber.”

A formal investigation into Blair began after de Menezes’s family complained that this was just one of several misleading claims made by the Met soon after the shooting.

Blair, who was appointed last year, is under pressure to resign over a series of misjudgments. Last month he was forced to apologise to Lord Goldsmith, the attorney-general, after it emerged that he had secretly taped a telephone conversation with him.

Beckley said last week that it would be inappropriate to discuss his evidence during the inquiry. “All I’ve done is explain what happened. Until the IPCC make a judgment on this I would prefer not to comment,” he said.

The IPCC is already examining testimony against Blair by Brian Paddick, a deputy assistant commissioner, who was closely involved in the police response to the July bombings.

He gave the IPCC a statement that directly contradicted Blair’s account. Paddick said he had been at Scotland Yard on the day of the shooting — the day after the failed July 21 suicide bombings in London — when he heard a member of Blair’s staff being told the wrong man had been shot.

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