Almost three-quarters of physicians are opposed to helping patients to die, according to a survey published today.

The findings by the Royal College of Physicians revealed members' widespread opposition to the assisted dying bill ahead of its second reading in the Lords this Friday.

The bill - introduced by the former human rights lawyer Lord Joel Joffe last autumn - outlines measures allowing doctors to give terminally ill patients wanting to end their lives a fatal dose to self-administer.

However, the revised legislation rules out euthanasia, in which a doctor would administer the dose to the patient.

The RCP - the organisation for doctors working in medicine rather than surgery - signalled its opposition to the bill, calling instead for a campaign for better care.

It surveyed 16,000 members, with a majority - 73.2% - opposing the bill. Just over a quarter (26%) of the 5,111 respondents believed a change in the law was needed.

Doctors working in palliative medicine, which seeks to give pain relief to terminally ill patients, were most likely to rule out a change in the law.

The RCP decided on its stance after being concerned that its previous position of neutrality had been interpreted as a gesture of support for a change in the law.

"Irrespective of whether the present bill is enacted or not, it should be seen as a further signal to campaign for better care for dying patients," the organisation said in a statement.

"This should include an extension of palliative care services and more discussion of life issues in the face of changing values, ethnic diversity and technological advance."

While the RCP has moved from a neutral stance to opposition, the British Medical Association, the doctors' trade union, softened its position to neutrality last summer following years of opposition.

The BMA said the matter was one for society and MPs, not just medical professionals.

Dignity in Dying, a pressure group aiming to give people choice over the right to die, said there was widespread public support for a change in the law. Polls have shown the proportion of those in favour of legalisation being as high as 82%.

Deborah Annetts, the organisation's chief executive, criticized the RCP findings and said the college's survey was "deeply flawed" and had been set up to achieve a "preordained finding".

The most recent major survey of all doctors in the UK showed almost two-thirds felt patients and doctors would be better protected by a more transparent law allowing patient choice, she said.

"This was a narrow and rapid 'consultation' on assisted dying ... the college gave its members only 48 hours to respond, and hence it is very unlikely that this is representative of doctors' views," she added.

"Indeed, we know of doctors who support Lord Joffe's bill who were not able to respond in the 48-hour timeframe."

However, John Sanders, the chairman of the RCP committee for ethical issues in medicine, rejected the claims.

"The main consultation was open for four weeks, and the accuracy of the validation exercise was demonstrated by the 48 hour responses in the main survey," he said.

"The college was scrupulous in process and strongly rejects that the survey was set up to deliver a predetermined conclusion."