A disabled athlete who has won five gold medals for Britain is to be deported to Nigeria tonight after the Government refused his 11th-hour plea for clemency.

Vincent Onwubiko, 43, a power-lifter from Lewisham, south-east London, who suffers from polio and is confined to a wheelchair represented Britain at a paraplegic games in 1995.

Mr Onwubiko came to the UK in 1994 and has an 11-year-old daughter. He claims that if he is sent back to Nigeria he will be dead within weeks.

Speaking from Colnbrook Immigration Removal Centre last night he told The Independent: "The Government has given me three months of painkillers for my return to Nigeria and told me to get on with it. But I need proper care. Sending me back is a death sentence."

He claims that his legal case is still before the courts and that he has been denied proper healthcare.

Mr Onwubiko represented Britain at the Stoke Mandeville Games in 1995 and 1997 and at the World Champion of Champions competition in Birmingham in 1996. He was also selected for the GB team at the 1996 Paralympics in Atlanta but was unable to attend.

But in 2007, Mr Onwubiko was sentenced to five months in prison for driving while disqualified after twice being convicted of careless driving in his specially adapted car, once after jumping a red light.

Under UK law, an immigrant who commits a serious criminal offence is subject to automatic deportation. At the end of his sentence Mr Onwubiko was arrested and taken to Dover Immigration Removal Centre, which he claims would not admit him because he does not have full use of his legs.

Instead he was taken to Brixton prison in south London. In January 2008, he was granted bail, but was re-arrested last August after being called in for an interview, and he has been in detention ever since.

This year his case was taken up by his MP, Bridget Prentice, who wrote to the UK Border Agency. She was told that there were "no grounds" to uphold his complaints about his treatment at Colnbrook and that the Home Office was committed to his deportation.

The removal order seen by The Independent says that Mr Onwubiko has been booked on a flight from Heathrow Airport to Lagos this evening.

In a final desperate bid to stay in Britain, Mr Onwubiko has written personally to Gordon Brown. He told Mr Brown: "I am a polio victim from childhood, which affected both my legs. Crippling my left leg totally and partially crippling my right leg, making it impossible for me to make use of my legs. Though I manage to get about on crutches and wheel-chair until some years ago when I sustained serious injury in my right hip while representing Britain in international disability weightlifting competitions."

He adds: "My request is for you to please use your good office to intervene by asking the Home Office to look into my case and release me because British national athletes are not supposed to be in an immigration centre."

David Wood, Head of Criminality and Detentions, UKBA said: "In light of a number of criminal convictions, Vincent Onwubiko was notified on 13 November 2007 of a decision to make a Deportation Order against him. Full consideration was given to his case and the decision was reviewed and upheld by an Immigration Judge.