If British police didn’t discover a parked silver Mercedes that was packed with gas containers and a large number of nails and terror attack did occur it would have caused "significant injury or loss of life," police said
A British security official told The Associated Press that there were similarities between the device and vehicle bombs used by insurgents in Iraq.
"Forensic staff are still examining the device, but once we know more about it, we'll know more about what type of individuals are behind this," said the official, who spoke on condition of anonymity because of the sensitivity of the security details.
The official said Britain's domestic spy agency MI5 also would examine possible connections between Friday's incident and at least two similar foiled plots _ including a planned attack on a West End nightclub in 2004 and a thwarted attempt to use limousines packed with gas canisters to attack targets in London and New York.
Officers were called to the Haymarket area near Piccadilly Circus shortly before 2 a.m., a police statement said. Sky News cited witnesses as saying doormen from a nearby nightclub had reported that someone had crashed a Mercedes sedan into garbage bins and had run away.
The Haymarket is the site of restaurants, bars, a cinema complex and theaters, and there would have been crowds in the area.
Prime Minister Gordon Brown, who took office on Wednesday, said the incident was a reminder that Britain faces "a serious and continuous threat" and the "need to be alert."
"I will stress to the Cabinet that the vigilance must be maintained over the next few days," Brown said.
The incident comes 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.