BBC's Brian Barron: "He says if he's jailed, he'll go on hunger strike"

The video tape was supplied by Dr Jack Kevorkian, known popularly as Dr Death, who says he has helped more than 120 people to die.

The footage, screened on CBS's 60 Minutes, apparently shows Dr Kevorkian giving an injection to 52-year-old Thomas Youk who was suffering from a chronic wasting disease.

He told the documentary that no country that considered itself enlightened would deem his actions a crime.

Dr Kevorkian, a 70-year-old retired pathologist, has been tried and acquitted four times for helping terminally ill patients to die.

He says he wants to provoke a legal showdown, although his former lawyer Geoffrey Feiger is trying to avert another courtroom battle.

Mr Feiger said: "Dr Kevorkian has served a valuable purpose in bringing this issue to the fore in terms of the needs of suffering people.

"But I don't think he will serve any purpose by martyring himself."

Two drugs

The footage showed the patient, Thomas Youk, 52, of Detroit, Michigan, twice signing a consent form after Dr Kevorkian asked whether he wanted the lethal injection to go ahead.

Viewers saw Dr Kevorkian administering two drugs, one to make the patient sleep and one to stop his heart.

In the broadcast, reporter Mike Wallace asked Dr Kevorkian, "You killed him?"

The doctor replied: "I did, but it could be manslaughter not murder.

"It doesn't bother me what you call it. I know what it is."

Some of Mr Youk's family took part in the 60 Minutes programme. His wife Melody said: "I was so grateful to know that someone would relieve him of his suffering.