Suspected bomb found in London
Police say the area will be closed for some time
Police have made safe a suspected car bomb in the heart of London.
Officers carried out a controlled explosion after reports of a suspicious vehicle parked in The Haymarket shortly before 0200 BST (0100 GMT).
The immediate area was cordoned off while police examined what they described as a "potentially viable explosive device".
There are unconfirmed reports that gas canisters were removed from the back of the car, close to Piccadilly Circus.
The government's emergency unit Cobra has called a meeting and the new Home Secretary Jacqui Smith is due to attend.
One police source said the bomb was a "big device" and posed a real and substantial threat to the area around The Haymarket, which is in London's theatreland.
A witness reported seeing gas canisters being removed from the car, believed to be a silver Mercedes, at around 0400 BST (O300 GMT).
Bouncers from a nearby nightclub said they saw the car being driven erratically before it crashed into a bin. They said the driver then got out and ran off.
Dozens of forensic officers were today poring over the scene, which was covered by a blue plastic police tent.
Scotland Yard said detectives from Counter Terrorism Command were investigating the potential bomb plot and will be checking the CCTV in the area.
A spokesman said: "Police were called to reports of a suspicious vehicle parked in The Haymarket, shortly before 2am this morning.
"As a precautionary measure the immediate area was cordoned off while the vehicle was examined by explosives officers. TRAVEL DISRUPTIONS
Piccadilly Circus tube station closed
Haymarket closed between Pall Mall and Piccadilly Circus
Buses diversions in the area with delays of more than 45 minutes
Heavy traffic around Trafalgar Square and Charing Cross Rd
Coventry St, Whitcomb St, Shaftesbury Ave and Cambridge Circus closed
"They discovered what appeared to be a potentially viable explosive device. This was made safe.
"The Metropolitan Police Counter Terrorism Command has launched an investigation."
Police say The Haymarket is likely to remain closed for some time and severe travel disruption is predicted.
'No intelligence'
Piccadilly Circus Tube station is closed and trains are not stopping, while local bus services are being diverted.
The BBC's Daniela Relph, at the scene, said the heart of London was completely closed off and police officers were concentrating on keeping people away.
People are unable to get to work
Thousands of commuters have been unable to get to work.
Professor Paul Wilkinson, a terrorism expert, said a passer-by had tipped off the police and officers would be concerned they did not have advanced intelligence.
Intelligence sources said they were keeping an open mind on who was responsible for the car bomb.
"All options, including the Irish, are open at this stage," said the source.
Defence Secretary Des Browne said: "It does appear to be a very serious incident.
"My first reaction to this is, thank God that we have police and explosives experts who can make these devices safe, and the arrangements they appear to have done, and that nobody has been injured."
Extra security measures have been put in place at Westminster, MPs and peers have been told.