Sky News television reported that a police officer seized a telephone from the first car -- believed to have been a potential detonator.
Around 3:30am, a second car parked on nearby Cockspur Street was ticketed and then towed to a lot on Park Lane, Clarke said. Police closed off Park Lane, reportedly after attendants smelled gasoline.
Clarke said police were examining footage from closed-circuit TV cameras, hoping the surveillance network in central London would help them track down the drivers of the Mercedes.
The CCTV footage will be compared with license plate recognition software, he said.
There had been no prior intelligence of planned al-Qaeda attacks, a British government official said on condition of anonymity because of the sensitivity of the investigation.
Also see story:
RSS