The widower of Diane Pretty, who lost her court battle for the right to have her husband help her to die, presented a 50,000-strong petition at Downing Street yesterday calling for a change in the law.

Brian Pretty, 46, from Luton, Bedfordshire, said his wife would have been "100% behind" the petition in favour of the right for terminally ill people to seek medical help to die.

Mrs Pretty, who had motor neurone disease, died aged 43 in May after taking her case to the House of Lords and the European court of human rights in Strasbourg.

Mr Pretty headed a group of four terminally ill people in handing over the petition.

The other campaigners were John Howard, 48, from Worthing, West Sussex, who has motor neurone disease, Steve Barksby, 51, from Manchester, who has Aids, Lisa Cook, 34, from Huddersfield, who has the gene which causes Huntington's disease and Jane MacDonald, 53, from north London, who has cancer and multiple sclerosis.

Mrs Cook said: "I've seen many of my family suffer a long and slow decline and I live every day with that knowledge that this is my future."

The presentation of the petition coincided with the launch of the campaign's website, www.UkActNow.Org