UPDATED 3.23pm: Police have shot a man dead at Stockwell Tube station while armed officers are searching a terraced house in west London.

Police said an operation in Harrow Road, West Kilburn, was linked to yesterday's failed bomb attacks.

In south London eyewitnesses say an Asian man was shot five times after being chased into Stockwell station.

One said the man "looked like a cornered fox" before he was caught by police.

Plain clothes officers chased the man from the street onto a Northern Line train.

One commuter said that the man fell into a carriage before officers pushed him to the floor and shot him five times in front of stunned passengers.

The man was also said to be wearing a baseball cap and a heavy coat.

The shooting comes as officers continue their search for four would-be bombers who yesterday attempted attacks at Oval, Warren Street, Shepherd's Bush stations and on a bus in Shoreditch, east London.

A 200-yard area around Stockwell station has been sealed off while forensic officers work inside. Police helicopters are hovering overhead.

Services on the Victoria and Northern lines, the two lines that run through the station, have been suspended after a request by police.

Gillian Breen, 39, was manning her fruit and vegetable stall at the entrance to Stockwell station when she saw armed police officers running inside.

About two minutes later flustered passengers came out. One woman "was so upset she was shaking", Ms Breen said.

"She said she was traveling by Tube on her way to work when she heard shots."

Before the passenger could say more, police ordered people to move away.

Sources said police had security concerns in the area before the shooting at 10am.

At Kennington armed officers surrounded a man while plain clothes officers were in the area.

Bomb threat at mosque

In east London a mosque was surrounded by police and local residents were told to stay indoors.

The East London mosque in Whitechapel High Street called police after it received a bomb threat at around 10.25am.

Mosque chairman Dr Muhammad Abdul Bari said the mosque and adjoining London Muslim Centre was evacuated.

The building was declared clear after a search by sniffer dogs.

"It is now business as usual, with Friday prayers proceeding as normal," Dr Bari said two hours later.

No police were in sight as Muslims arrived for their midday prayers.