Mr Prescott, who celebrated his 69th birthday last Thursday, has undergone medical tests, but his condition is not thought to be life-threatening.

He has cancelled plans to host the launch of a trans-Atlantic voyage to mark the 200th anniversary of the abolition of the slave trade.

The DPM, a former seaman, was due to meet young people from the former slave ports of London, Liverpool and Bristol chosen to join the crew of the Amistad Freedom Schooner, a replica of an 18th-century slaving vessel.

But he sent a message from his hospital bed, apologising for being unable to attend the event at Admiralty House in London and wishing the project well.

Mr Prescott's office has declined to confirm reports that he was taken ill on a train travelling between his Hull constituency and London, or to reveal the location of the hospital where he is being treated.

In a statement, his office said: "The DPM was taken ill earlier today. He has been admitted to hospital. He is undergoing tests as a result of a suspected chest infection."

Mr Prescott, who will leave office along with Prime Minister Tony Blair on June 27, last week returned from a tour of America and the Caribbean, where he visited Jamaica and Barbados.

He has generally enjoyed robust health in his 10 years as DPM, with only a few bouts of illness.

He was admitted to Castlehill hospital in Hull on Christmas Day last year suffering from a kidney stone, and was released later the same day. And he has also suffered from Type 2 diabetes for a number of years, which he manages with medication. His condition was made public in 2002.