LONDON - British cosmologist Stephen Hawking has backed the right for people who are terminally ill to choose to end their lives and to receive help to do so as long as safeguards are in place.
The wheelchair-bound Hawking was diagnosed with motor neurone disease aged 21 and told he had two to three years to live. Now 71, he is one of the world's leading scientists, known especially for his work on black holes and as author of the international bestseller "A Brief History of Time".
Speaking ahead of the release of a documentary about his life this week, Hawking said he backed the right to die but only if the person involved had chosen that route.
He recalled how he was once put on a life support machine after suffering pneumonia and his wife was given the option of switching off the machine but this is not something he wanted.
"I think those who have a terminal illness and are in great pain should have the right to choose to end their lives, and those who help them should be free from prosecution," Hawking told the BBC.
"There must be safeguards that the person concerned genuinely wants to end their life and are not being pressurized into it or have it done without their knowledge and consent as would have been the case with me."
Assisted suicide is illegal in Britain and the issue of whether or not to decriminalize it for people whose lives are unbearable is a matter of debate in many countries.
Right-to-die advocates say people capable of making that decision should be allowed to die with dignity. Opponents say liberalizing the law could leave vulnerable people at risk.
Switzerland and several US states are among places where some forms of euthanasia or assisted suicide are legal under certain circumstances.
Hawking, who has made guest appearances in TV shows such as The Simpsons and Star Trek, says his active mind and sense of humour are key to his survival.
Hawking communicates via a cheek muscle linked to a sensor and computerized voice system. He urged anyone with a disability to focus on what they can do and not regret what they cannot do.
"Theoretical physics is one field where being disabled is not a handicap. It is all in the mind," said the scientist, who works at Cambridge University.
The documentary "Hawking" by Vertigo Films is due to be released in Britain on September 20.