Medical organisations said yesterday that Labour proposals to persuade patients to take more responsibility for their health could turn into a bureaucratic nightmare.

Smokers and the overweight are among those who could be asked to sign agreements with doctors to take more exercise or to eat more healthily. In return doctors would agree to provide all necessary treatment, offering appointments and keeping delays to a minimum.

The proposals, set out by Labour in a policy paper posted on its website, stress that patients will not be refused care. "The idea [is] not to exclude patients from care but to remind them of the need to use the health service - a free and finite resource - responsibly," it says.

A Labour Party spokesman ridiculed claims that fat people would be denied treatment if they failed to lose weight - but he agreed that some form of sanction would be needed to make patients take their responsibilities seriously.

"If you have a right to a booked appointment with your GP within 48 hours then you have a responsibility to turn up. If someone doesn't turn up three times in a row then the receptionist might tell them that they will be seen at a time convenient to the doctor."

The policy document contains a suggestion from Labour's Worcester policy forum that fines should be imposed on patients who break appointments.

The spokesman said smokers were already required to commit to giving up if they wanted NHS treatment. He said: "If you go to your doctor for nicotine patches you don't just get the patches. There is a programme of smoking cessation and you have to agree to the whole thing.

"This is a serious political debate about how we change the relationship between public services and individual members of the public to one where people understand the rights we enjoy depend on the duties we owe."

The British Medical Association said it backed efforts to reduce pressure on the NHS - but said it would not want to see anything that added to the mountain of bureaucracy that already existed. Dr John Chisholm, chairman of the BMA's General Practitioners Committee, said the proposals appeared to threaten the doctor-patient relationship. He added: "At a time when we are working with the Government to reduce bureaucracy in general practice, this idea amounts to a bureaucratic nightmare."

The anti-smoking group Ash warned that nicotine was so highly addictive, to give up was often extremely difficult. "We don't want to get into a blame culture where we are criticising people for their lifestyle," a spokeswoman said.

Dieticians in Obesity Management UK said: "There's nothing like being told to do something to make you dig your heels in and not do it."

The policy paper is one of five put out for consultation. It is due to be discussed at Labour's annual conference and could form part of the party's manifesto at the next election.