Media playback is unsupported on your device Media caption Jeremy Paxman challenges Pratchett on the issue of assisted suicide.

Sir Terry Pratchett has said witnessing a man being helped to die for a controversial BBC film has not affected his support for assisted suicide.

In Choosing to Die, the 63-year-old author - who has Alzheimer's disease - went to Switzerland to see a British man with motor neurone disease dying.

Liz Carr, a disability campaigner, said it was pro-suicide propaganda and that she was surprised the BBC had made it.

The BBC said Monday's film would help viewers make up "their own minds".

The programme, showed Peter Smedley, a 71-year-old hotelier, travelling from his home in Guernsey to Switzerland and taking a lethal dose of barbiturates given to him by the Dignitas organisation.

Dignity of life

Sir Terry, who made the film to establish whether he would be able to die at a time and in a way he wanted, said seeing what Dignitas did had not changed his mind.

It is up to you to decide whether his last moments are deeply moving, distressing, or rather ordinary Charlie Russell, Director of Choosing to Die Read Charlie Russell's blog on making the film

"I believe it should be possible for someone stricken with a serious and ultimately fatal illness to choose to die peacefully with medical help, rather than suffer," he told BBC's Newsnight.

Asked about the sanctity of life, Sir Terry responded: "What about the dignity of life?" Lack of dignity would be enough for some people to kill themselves, he said.

He added that he believed the right to an assisted suicide should extend to anyone over the age of consent.

He also accused the government of "turning its back" on the issue of assisted suicide.

"I was ashamed that British people had to drag themselves to Switzerland at some considerable cost," he said.

The BBC denied the screening could lead to copycat suicides and said it would enable viewers to make up their own minds on the subject.

The documentary maker Charlie Russell said the decision to film Mr Smedley dying had been given a lot of thought.

"As a film maker I felt it was the truth and unfortunately we do all die," he said. "It's not very nice but that's what happens to us all."

Ms Carr said: "I and many other disabled older and terminally ill people, are quite fearful of what legalising assisted suicide would do and mean and those arguments aren't being debated, teased out, the safeguards aren't being looked at.

I want to see much more emphasis put on supporting people in living, than assisting them in dying Right Reverend Michael Langrish, Bishop of Exeter

"Until we have a programme that does that, then I won't be happy to move onto this wider debate."

The Bishop of Exeter, the Right Reverend Michael Langrish, said: "I want to see much more emphasis put on supporting people in living, than assisting them in dying."

He said: "The law still enshrines that sense of the intrinsic value of life. But the law ultimately is not there to constrain individual choice. It's there to constrain third party action and complicity in another person's death.

"That remains illegal. There may be ameliorating circumstances that can be taken into account. But the law remains clear and is there to protect the vulnerable."

Debbie Purdy, who has multiple sclerosis, went to court to protect her husband from prosecution if he accompanies her to Dignitas.

'Quality of life'

She said in a debate after the programme: "Politicians haven't kept up.

"Lawyers and judges have been the only people who have been prepared to defend my rights... and my right to life and the quality of my life is the most important thing to me."

In the last 12 years 1,100 people from all over Europe have been "assisted to die" by Dignitas.

A spokeswoman for the pressure group Dignity in Dying said it was "deeply moving and at times difficult to watch".

She said: "It clearly didn't seek to hide the realities of assisted dying. In setting out one person's views on assisted dying, it challenges all of us to think about this important issue head on and ask what choices we might want for ourselves and our loved ones at the end of life."

She said the current legal situation in the UK meant "not only are people travelling abroad to die, but there are also those who are ending their lives at home, behind closed doors, or with the help of doctors and loved ones who are helping illegally."

'Propaganda'

Dignity in Dying is calling for an assisted dying law with "upfront safeguards".

But Alistair Thompson, a spokesman for the Care Not Killing Alliance pressure group, said: "This is pro-assisted suicide propaganda loosely dressed up as a documentary."

Campaigners claim it is the fifth programme on the subject produced by the BBC in three years presented by a pro-euthanasia campaigner or sympathiser.

Mr Thompson said: "The evidence is that the more you portray this, the more suicides you will have.

"The BBC is funded in a different way to other media and has a responsibility to give a balanced programme."

The BBC denied it was biased on the issue and a spokeswoman said the documentary was "about one person's experience, Terry's journey exploring the issues and the experience he is going through".

"It is giving people the chance to make their own minds up on the issue," she added.

A Ministry of Justice spokesman said: "The government believes that any change to the law in this emotive and contentious area is an issue of individual conscience and a matter for Parliament to decide rather than government policy."

The documentary, Choosing to Die, and the debate on BBC's Newsnight are both available to watch on BBC's iPlayer.