Britain was put on high alert for terrorist attacks yesterday after a car bomb exploded outside the BBC's London headquarters.

The blast in the early hours at BBC Television Centre in west London was part of an ongoing campaign of "murderous attacks" by the Real IRA, said Deputy Assistant Commissioner Alan Fry, head of the Anti Terrorist Branch.

The dissident terror group were responsible for the August 1998 Omagh bombing in which 29 people were killed.

"It is quite clear that we are dealing with ruthless terrorists who are prepared to use ruthless tactics without any care for the consequences of their actions," Mr Fry said.

Police arrived at the BBC after two coded warnings were received, one at a London hospital and another at a charitable organisation, saying a bomb had been planted.

Only the prompt action of the emergency services in evacuating the BBC building and local residents avoided certain death as the blast from 10-20lbs of high explosives damaged nearby buildings.

Experts were trying to conduct a controlled explosion when the bomb detonated, leaving one railway worker with minor injuries.

The device was packed inside a red taxi with a black roof - registration D902 GYH - that was parked outside the BBC main entrance on the wrong side of the road with its headlights on.

It had been bought by a man who spoke with a Northern Irish accent from a dealer in Edmonton, north London, for £300 on Saturday morning. He was white, about 30 years old, 6ft tall, wearing a short jacket and a baseball cap.

Detectives are linking the blast to last year's bomb at Hammersmith Bridge, a controlled explosion on a railway line at Acton and the mortar attack on the MI6 building at Vauxhall, London