The guidelines, the first to be published as part of the government's anti-smoking strategy, were unveiled by Public Health Minister Tessa Jowell on Thursday.

They are contained in the Health Education Authority (HEA) report, Smoking Cessation Guidelines for Health Professionals, published in the British Medical Journal.

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The HEA says the guidelines could save the NHS millions.

As part of a health blitz on smoking, they recommend that:

• Health workers should question patients about whether they smoke at every opportunity;
• Advise all smokers to stop;
• Offer simple tips on how to give up and encourage smokers to use nicotine replacement therapy (NRT);
• Refer patients to specialist non-stop smoking services where appropriate.

The HEA says smoking costs the NHS in England �1.5bn a year - �14m for each health authority - and causes more than 120,000 deaths, from illnesses such as cancer and heart disease.

At least 330 people a day die from smoking.

A comprehensive strategy to help smokers quit would cost health authorities' just �330,000 a year, making a huge saving if it was successful.

Seven in 10 want to give up

The HEA report, which is based on studies in the USA and the UK, estimates that if GPs asked 50% more patients than they do currently about their smoking habits and gave advice it could help 18 people in each five-partner practice to give up.

This would mean 75,000 more people in England would quit smoking. The government says seven out of 10 smokers want to give up.

The strategy is the first of a series of steps following the government's White Paper on Tobacco, launched last month.

The government has announced an extra �60m over the next three years to develop services to help people stop smoking, including stop-smoking clinics and free NRT for deprived areas.

Nicotine replacement

The HEA says NRT doubles a person's chances of being able to quit smoking.

Tessa Jowell said: "The government's White Paper, 'Smoking Kills', sets out for the first time the way in which a programme of systematic help will be available to smokers through the NHS.

GPs are advised to ask routinely about smoking

"Smoking cessation is a skilled business and it is important that investment is made on the best evidence of good results."

Dr Ann McNeil, co-author of the report which has been reviewed by 19 international experts, said: "The NHS has a central role to play in reducing the number of people who smoke and health professionals need to take every opportunity to talk to patients about smoking.

"There is overwhelming evidence that they can really help people to quit smoking. These guidelines show health authorities what can be done and how cost-effective it is."

Doctors already ask about smoking in relation to certain illnesses, but the guidance suggests this should become more routine.

A spokeswoman for the British Medical Association said: "It is good to see smoking cessation guidance which can be used consistently by all health care professionals in primary care."

Professor George Alberti, President of the Royal College of Physicians, which has endorsed the guidelines, welcomed their introduction:

"The new guidelines show that saving lives needn't always be as dramatic as emergency resuscitation, it can also happen by offering long-term support to people who want to improve their own health by giving up smoking.