British bomb squads dismantled two car bombs in the heart of London Friday, as a Scotland Yard spokesman said they were "clearly linked" and packed with enough fuel and explosives to cause major carnage.

Explosives experts haul away one of two bomb-rigged Mercedes that were found Friday in The Haymarket in the Piccadilly area of central London.
(Clara Molden/Associated Press)

Peter Clarke, the head of the London force's counter-terrorism unit, said the first car — a Mercedes parked in The Haymarket, a bustling entertainment district that runs between the Piccadilly Circus and Trafalgar Square landmarks — would have caused "significant injury or loss of life," possibly killing hundreds of bar-hoppers.

The second vehicle — also a Mercedes — was found on a nearby street and contained "very similar materials to those that had been found in the first car in The Haymarket," Clarke later said during a brief news conference Friday afternoon.

Like the first car, the second was packed with gasoline, gas canisters and "a substantial quantity of nails," Clarke said. Had it detonated, the blast would have led to a "considerable loss of life," he said.

"The discovery of what appears to be a second bomb is troubling," said Clarke, the deputy assistant commissioner of Scotland Yard.

Cars discovered by chance

It appeared that, much like the discovery of the first bomb, London police were tipped off to the vehicle only by chance.

After a parking enforcement officer ticketed a Mercedes of the same make as the first vehicle, there were reports that it smelled of gasoline. Bomb squads were called to the impound lot in Hyde Park and seized the car.

In the first instance, an ambulance crew that was treating a patient at about 1:30 a.m. spotted vapour coming from a metallic-blue sedan parked nearby, outside the Tiger Tiger nightclub, and alerted police.

Transit authorities closed Piccadilly Circus underground train station for hours after the first rigged vehicle was found.

'Too early to speculate' on suspects

Clarke said the gas cylinders were being inspected at a police laboratory, but would not speculate what they contained. Investigators were going through "massive" amounts of closed-circuit television footage and forensic evidence left at the scene, he added.

Britain is 'clearly facing the most serious and sustained threat to our security from international terrorism.' —British Home Secretary Jacqui Smith

It was "too early to speculate" who might have been responsible for the bomb, Clarke said.

"We will keep an open mind," he said.

Clarke urged the public to remain vigilant and alert authorities through a confidential anti-terrorist hotline if they had any knowledge of the plans or witnessed something suspicious.

In an Associated Press report, a British security expert speaking on condition of anonymity said the style of the bomb reminded explosives experts of vehicle bombs planted by insurgents in Iraq. It is believed packing nails with the bomb in the Mercedes was meant to maximize damage that would have been caused by shrapnel.

Must stay vigilant, new PM warns

New British Home Secretary Jacqui Smith told reporters that Britain was "clearly facing the most serious and sustained threat to our security from international terrorism."

Smith, who was named to the cabinet on Wednesday by new British Prime Minister Gordon Brown, met with Britain's Cobra emergency unit after the first car was found to discuss the threat.

Brown said the case was a reminder that Britain faces "a serious and continuous threat" and that there is a "need to be alert."

'I will stress to the cabinet that the vigilance must be maintained over the next few days.'
—Prime Minister Gordon Brown

"I will stress to the cabinet that the vigilance must be maintained over the next few days," Brown said.

The discovery of the rigged cars came a week before the second anniversary of the July 7 London bombings, when four British Muslim suicide bombers killed themselves and 52 bus and subway passengers.

For more than a year, the government has held the country's terrorist threat level at severe — which means a terrorist attack is highly likely.

With files from the Associated Press