Britain?s most senior policeman, Ian Blair, defended yesterday his handling of the fatal shooting of a Brazilian electrician by his officers, insisting he had still believed the dead man was a suicide bomber 24 hours after the killing. London?s police chief has come under heavy pressure over the July 22 killing of 27-year-old Jean Charles de Menezes on an underground train.

Leaked documents from the investigation into the case have exposed blunders and cast doubt on initial accounts from police and witnesses. The shooting took place with the capital on edge, the day after a failed attempt to repeat suicide bombings by four British Muslims that killed 52 people on July 7.

?At that time - and for the next 24 hours ? I and everybody who advised me believed the person who was shot was a suicide bomber,? Blair told the News of the World newspaper. He said it was not until the morning after the shooting that he was informed an innocent man had been killed.

Inquiry must proceed

Relatives of de Menezes have called on Blair to quit because of police mistakes and information they say was misleading. Their lawyers have voiced doubts that senior officers did not know the truth soon after the shooting. ?We express incredulity that the senior police officer would have made extravagant claims from the outset without first informing themselves of the true facts?, lawyer Gareth Peirce said.

Government ministers said an independent inquiry must be allowed to proceed without prejudgment. ?It was a terrible tragedy that that young lad was killed but ... an independent inquiry is underway. Let us wait for the facts?, Deputy Prime Minister John Prescott told BBC Television.

Blair defended his actions as two newspapers reported that units involved in the killing were blaming each other. The Observer and Sunday Mirror said undercover officers who followed de Menezes - after he left an apartment block under observation after the botched bombings - did not believe he posed an immediate threat. The officers were shocked when armed police shot him at Stockwell station in south London, the reports said, citing senior police sources.

?A high state of alert?

But the armed officers maintain they would not have shot the man if he had not been openly identified to them by the surveillance team, the Mirror said. Newspapers also reported that British intelligence chiefs had downgraded their assessment of the threat of a fresh terrorist attack on London from ?critical? to ?severe general?. That assessment was similarly relaxed shortly before the July 7 bombings. ?We don?t comment on that?, Prescott said. ?We are in a high state of alert which we need to be.? On the day of the shooting, Blair said it was ?directly linked to the ongoing and expanding anti-terrorist operation?.

In yesterday?s interview, Blair stressed he had apologised for the killing and was concerned for the de Menezes family. ?But what concerns me is that this part of the story is concentrating on the death of one individual, when we have 52 dead people?, he said. ?We have to concentrate on how we find the people who are helping or thinking about planning further atrocities.?