A British pensioner has become the first person to die at the Swiss-assisted suicide clinic Dignitas because he was suffering from dementia.

The 83-year-old man, who has not been named, decided to travel to Zurich to end his life after being diagnosed with the degenerative incurable disease.

He made the decision because he could not face living with the disease or the burden it would have placed on his family.

He is believed to be the first person to have used the clinic's services purely because of dementia. It is thought he died seven weeks ago after a psychiatrist had compiled a report saying he was mentally competent. His story has only just been revealed.

Dr Michael Irwin, a retired GP who campaigns for the right to die, said the pensioner was "grateful" to be able to end his life.

In an interview with the Mirror, Irwin said: "His wife said he was grateful. His family were 100% behind him. I have spoken to his widow since and she felt that it was handled in a very dignified and proper manner.

"She is extremely happy about how everything was arranged."

"I have been four times with people to Switzerland. Two were terminally ill, one was very disabled and one was in her mid-80s so I have seen how it is handled by the Swiss. It is a very dignified procedure."

"You have got to be a very determined person to be able or willing to make that kind of journey.

Illegal in the UK

"He knew of how things would deteriorate and took what I think is a sensible decision both for himself and his family."

Assisted suicide is illegal in the UK and carries a maximum prison sentence of 14 years.

Last year Tony Nicklinson, who suffered from locked-in syndrome following a stroke in 2005, lost his high court battle to end his life in his own home. He died from pneumonia a few weeks later after refusing to eat.

In April, quadriplegic Paul Lamb took up Nicklinson's fight and has launched a new legal battle with the backing of Nicklinson's widow.

A spokesman for Care Not Killing said the dementia case was "hugely alarming".

It shows the real agenda of those seeking a change in the law," the spokesman said. "What they are looking for is assisted suicide or euthanasia almost on demand.

"We've been warning about an incremental approach, as once you change the law you get more and more cases like this, which is why we are so worried.

"We know that people who are vulnerable, disabled and terminally ill will be most under pressure."

The Samaritans urge anyone feeling distressed and feels the need to talk to somebody to call them on 08457 90 90 90 or email jo@samaritans.org