A commission probing last year's tube shooting in which British police shot dead a Brazilian after mistaking him for a terrorist was told by witnesses that senior officials suspected within hours of the incident that the deceased was innocent, a media report said Thursday.

The witnesses, who were at the Scotland Yard's headquarters a day after the incident, told the Independent Police Complaints Commission that senior police officers had suspected within hours that they shot the wrong man.

The revelations have raised questions about Metropolitan Police Commissioner Ian Blair's repeated assertions that he was unaware that Menezes was not a suicide bomber until 24 hours after he was shot.

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One of the witness, a senior police source, told the IPCC that by the afternoon (after the shooting), top officers were working on the assumption that "we got the wrong person... we better plan around this being a mistake," the Guardian newspaper reported.

Another source said every senior officer he spoke to believed that the man killed -- Jean Charles De Menezes -- was not a terrorist. "I don't know how Ian could not have known."

Menezes was killed on a tube train on July 22, by officers who believed that he was a terrorist who had tried to attack London's [Images] transport system the day before.

The IPCC is also probing into the conduct of Sir Ian, in response to a complaint by de Menezes' family who alleged that he and others tried to mislead the public about the shooting. The revelations come as Brazilian President Luiz Inacio Lula da Silva visits Britain and after yesterday's backing for Sir Ian's shoot-to-kill policy by the Association of Chief Police Officers.