Senior police officers said yesterday there would be no change to a controversial shoot-to-kill policy after an innocent man was gunned down.
Scotland Yard Commissioner Sir Ian Blair apologised to the family of Brazilian electrician Jean Charles de Menezes, 27, in what was a major setback for anti-terrorist police.
But he refused to revoke officers' licence to kill and admitted more people may die as a result.
As the hunt intensified for four bombers who failed to detonate their devices on three tube trains and a bus last Thursday, Home Secretary Charles Clarke said he was postponing his family holiday.
The revelation that he had been planning to leave his desk at all added to controversy over MPs' 80-day summer break when the country is facing a terrorist crisis.
In Little Wormwood Scrubs, north-west London, the bomb squad carried out controlled explosions on a package found hidden in bushes.
They believe it may have been a fifth bomb linked to the devices that failed to go off last Thursday.
Victims' relatives from the previous set of attacks on July 7 made an emotional pilgrimage to the four sites where their loved ones were killed or injured.
And more than 230 of them attended a briefing on the investigation with senior police officers. As they left, some of them were in tears and had to be comforted by relatives.
Detectives are continuing to probe links between the July 7 bombers, who killed 52 people, and those who tried to bring further carnage to London last week.
They believe some of the second team may have attended a pre-mission bonding session with July 7 bombers Mohammad Sidique Khan and Shehzad Tanweer at the National Whitewater Centre, near Bala, north Wales.
In London, a cousin of Mr de Menezes wept as he re-enacted the shooting victim's final movements to show how it could have been anyone who was shot.
Alex Pereira, 28, left his cousin's flat in Tulse Hill, walked for five minutes and then got the number 2 bus to Stockwell station.
There, in a furious condemnation of the police, he said: ''Police had plenty of time to stop him. If they were so afraid of a bomb, why did they let him get on the bus.''
At Scotland Yard about 30 protestors, including friends of the dead man, gathered and sang the Brazilian national anthem.
Police said a contributory factor to Mr de Menezes being shot was the chunky top he was wearing, which could have hidden a bomb and was out of place on a warm day.
But friend Fausto Soares said: ''We come from a hot country and this is a cold country.
"I wear my jacket 365 days a year. I'm wearing a jacket now and after what's happened, I don't feel safe.''
He said he did not know why Mr de Menezes, who was in the country legally, bolted and tried to get on a train when challenged by undercover armed police at the entrance to the station.
''What we want to know is why they threw him on the floor and shot him in the head five times,'' he said.
The Brazilian Government said it was a lamentable mistake by the British police.
Foreign Secretary Jack Straw spoke to his counterpart Celso Amorim, who is in London and who demanded a full investigation.
Apologising to the dead man's family Sir Ian Blair said: ''This is a tragedy. The Metropolitan Police accepts full responsibility for this. To the family I can only express my deep regrets.''
The officer who fired the fatal shots has not been suspended but has been taken off firearms duty as a matter of routine while an investigation is carried out.
Sir Ian defended his officers' action, saying: ''What we have got to recognise is that people are taking incredibly difficult, fast-time decisions in life-threatening situations.
''It wasn't just a random event and what's most important to recognise is that it's still happening out there. There are still officers out there having to make those calls as we speak.
''Somebody else could be shot, but everything is done to make it right.
''The important thing here is there is nothing gratuitous going on, there is nothing cavalier here, there is no conspiracy to shoot people.''
He said the ''shoot-to-kill in order to protect'' policy would go on with officers told to aim for the head.
''There is no point in shooting at someone's chest because that is where the bomb is likely to be. There is no point in shooting anywhere else if they fall down and detonate it. The only way to deal with this is to shoot to the head,'' he said.
* Three men have now been arrested in Stockwell and Tulse Hill in connection with the July 21 attempted attacks. They are being held at high security Paddington Green police station, in London,. None of them are thought to be the would-be bombers.
Family's grief - Page 4
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