The husband of Diane Pretty, who failed to win the right to be helped to die, is continuing his late wife's campaign for a change in the law.

Brian Pretty, along with a group of terminally ill campaigners, delivered the petition containing around 50,000 signatures to Downing Street, along with a personal letter to Prime Minister Tony Blair, pressing for the change.

Mrs Pretty, 43, a mother of two from Luton who had motor neurone disease, died in May this year.

The couple, backed by the Voluntary Euthanasia Society and the civil rights group Liberty, had taken their campaign all the way to the European Court of Human Rights, after being defeated in a series of UK courts.

Mr Pretty risked prosecution if he defied the courts and helped his wife die.

I would like the opportunity to choose the time and place of my death if life becomes unbearable

Jane McDonald

He is now leading a nationwide campaign - Act Now -calling for the law to be changed to allow the terminally ill to be able to choose to have medical assistance to die.

Speaking outside Downing Street, Mr Pretty said: "We are calling for Tony Blair to listen to the people who are asking for a change in the law.

"Diane would be 100% behind this as she was from the start."

He told the BBC the legal side of the battle had been exhausted, but he hoped public pressure would lead to the government changing the law.

"It's about time they started listening."

Mr Pretty, 46, from Luton in Bedfordshire, added: "When my wife Diane died last May I watched her go through everything she had foreseen and hoped to avoid.

"She had spent nearly a year battling through the courts for the right to choose how and when she died in order to avoid all that suffering.

Seeking support

He was joined at Downing Street, and a later meeting at Conservative Central Office, by Jane MacDonald, who has cancer and multiple sclerosis, John Howard, who has motor neurone disease, Steve Barksby, who has Aids, and Lisa Cook, who has the Huntingdon's gene.

The event marks the start of a nationwide campaign to get the law changed.

UK Act Now has written to every MP, asking for their support.

Brian Pretty is leading the fight for a change in the law

It is also launching a website on which terminally ill people and their families will tell their stories.

Jane MacDonald, who is from North London, said: "For now, the quality of my life is reasonable but as a nurse I am aware that despite the best medical care and the finest hospices there is a chance of dying in pain and distress with a loss of my personal dignity.

"I would like the opportunity to choose the time and place of my death if life becomes unbearable."

Public backing

UK Act Now claims opinion polls over the last decade have consistently shown over 80% of people agree that the law should be changed.

At the time of Mrs Pretty's death, Liberal Democrat Euro-MP Chris Davies, who supported her in her legal fight, said her life should be commemorated with an Act of Parliament creating a legal basis for assisted suicide.

Mr Davies, the MEP for the North West MEP said: "Diane Pretty's courageous battle has highlighted the need for a long overdue reform of the law.

"People in her situation should have the right to choose for themselves to die with dignity and without suffering."

But Rachel Hurst, director of Disability Awareness in Action, said it would be "very wrong for justice to say in certain circumstances people can die".

"It would be a slippery slope and many people who did not want to die could be affected," she said."