Biggs, 70, was taken to hospital in Rio de Janeiro last month after suffering a mild stroke. His first, more severe stroke was in March last year, from which he recovered.
Two months ago he allowed television cameras into his home to film celebrations for his 70th birthday. Several of his former criminal associates including the mastermind of the Great Train Robbery, Bruce Reynolds, flew out from Britain for the occasion.
For a generation Biggs became a symbol of defiance, living unmolested in Rio de Janeiro after escaping from Wandsworth prison in south London by scaling a wall and making his getaway in a removals van.
He had served just 15 months of a 30-year sentence for his part in the robbery in 1963 of pounds 2.6m - pounds 30m at today's prices - from a Glasgow to London train. The driver, Jack Mills, was badly injured after being hit with iron bars. He died in 1970, the year Biggs settled in Brazil.