Biggs has suffered a series of strokes and minor heart attacks

Biggs, 75, who cannot speak after several strokes and minor heart attacks, is held at Belmarsh prison and receives 24-hour nursing care.

Legal adviser Giovanni Di Stefano said Biggs "did not belong in prison".

Biggs was sentenced to 30 years for his part in the raid on the Glasgow to London mail train on 8 August, 1963.

His solicitors have written to Home Secretary Charles Clarke to ask for his release on compassionate grounds in view of the prisoner's "age and infirmity".

On the run

Mr Di Stefano said his client would be on home detention in any other European country.

He added: "If the home secretary can release the most supposed dangerous terrorists from Belmarsh why cannot he let this old man go?"

Belmarsh is a category A prison and this is the latest in a series of attempts by Biggs' legal team to get him transferred to a lower security prison or have him released.

The robber fled Britain after escaping from Wandsworth prison in a furniture van after just 15 months in jail.

Biggs used plastic surgery to change his appearance and fled to Spain, Australia, and then Brazil.

He surrendered himself back into custody in 2001 after spending 36 years on the run.