Britain's notorious "Great Train Robber" was released from his prison sentence Thursday as the nearly 80-year-old lay close to death in a hospital bed.

Britain's Justice Secretary Jack Straw said he decided to release Ronnie Biggs on compassionate grounds, after he fell seriously ill this week in his cell at Norwich Prison, 118 miles northeast of London.

The prison officers watching him at the Norwich and Norfolk Hospital will remain overnight, and leave tomorrow, once the paperwork for his release is complete, Straw said. Biggs turns 80 on Saturday.

Biggs was part of a gang that robbed a Glasgow-to-London mail train in August 1963, in what was called the "heist of the century." The robbery netted 2.6 million pounds — worth more than $50 million today.

Most of the gang was soon rounded up. Biggs was sentenced to 30 years in jail but escaped from prison in 1965 by climbing over a wall. He fled to Brazil, where he made a living from his notoriety, regaling journalists and tourists with stories of his exploits and even recording with punk band The Sex Pistols.

In 2001, he voluntarily returned to Britain, surrendered to police and was sent back to jail. He was locked up in Belmarsh high-security prison in London on his return before being moved to a specialist medical unit at Norwich prison

He has suffered a series of strokes and a broken hip, and is being treated for pneumonia. He is now bedridden, fed through a tube, and barely able to communicate.

His lawyers sought to have him released, arguing that his age and severe health problems mean he is no longer a threat.

He became eligible for parole last month after he served a total of 10 years of his 30-year sentence, but Straw overruled a parole board recommendation that Biggs be freed, saying that he was "wholly unrepentant" about his crimes.

Straw said that Biggs' condition changed his mind.

"The medical evidence clearly shows that Mr. Biggs is very ill and that his condition has deteriorated recently, culminating in his readmission to hospital. His condition is not expected to improve," Straw said in a statement. "It is for that reason that I am granting Mr. Biggs compassionate release on medical grounds."

Straw said Biggs must now live at an approved address and cannot travel abroad without approval from British authorities.