A man shot dead by police hunting the bombers behind Thursday's London attacks was unconnected to the incidents, police have confirmed.

The man was killed in Stockwell Tube station in an incident described by Scotland Yard as a "tragedy".

Two other men have been arrested and are being questioned after bombers targeted three Tube trains and a bus.

Police have also raided a house in Streatham Hill, south London, in connection with the failed attacks.

'Horrendous consequences'

A Scotland Yard statement read: "We believe we now know the identity of the man shot at Stockwell Underground station by police on Friday 22nd July 2005, although he is still subject to formal identification.

"We are now satisfied that he was not connected with the incidents of Thursday 21st July 2005.

"For somebody to lose their life in such circumstances is a tragedy and one that the Metropolitan Police Service regrets."

The statement confirmed the man had been followed by police from a house in Tulse Hill that was under surveillance.

His death is being investigated by officers from the MPS Directorate of Professional Standards, and will be referred to the Independent Police Complaints Commission.

John O'Connor, former commander of the Met Police, told the BBC the consequences of the shooting were likely to be "quite horrendous".

He said he expected officers to face criminal charges, and other officers could even refuse to carry weapons.

But Shami Chakrabarti, director of human rights group Liberty, said it was too early to judge what the effects would be.

She called for a "prompt, comprehensive and independent investigation".

Arrests

Police announced on Saturday evening they have raided another property in south London.

The house is currently being searched and it is believed armed officers are there, but no arrests have been made.

Two men are still being held at Paddington Green police station, central London, in connection with Thursday's attacks.

The first man was arrested at around 1630 BST on Friday during a raid on a block of flats near to Oval and Stockwell Tube stations.

Eyewitnesses said he was led away with a woman and child.

The second man was arrested late on Friday night, also in the Stockwell area.

Both are being held under anti-terrorism legislation which gives police 14 days before they have to bring charges.

CCTV images

Scotland Yard said they had been contacted by over 500 members of the public following the release of CCTV footage of four suspects.

Detectives said they were hopeful of useful lines of inquiry coming from the calls and e-mails.

Three devices found after the failed bombings were the same size and weight as those used in the suicide attacks of 7 July, which killed scores.

The fourth was smaller, apparently contained in a plastic box. The same chemicals appear to have been used.

They targeted Oval, Warren Street and Shepherd's Bush stations and a bus in Hackney.

The Hammersmith and City line train was removed from Shepherd's Bush station on Saturday afternoon.

Transport for London said it hoped to have trains running on the line from Paddington to Hammersmith on Saturday evening.

PHOTO CAPTION

Armed police officers walk through a garden on a housing estate during a raid on a house in Brixton, south London, July 23, 2005. (REUTERS)