The finding comes as No Smoking Day gets under way on Wednesday.

Smoking is estimated to be responsible for 90% of lung cancer cases.

The NOP poll, comissioned by Macmillan Cancer Relief, questioned 600 smokers aged between 16 and 54.

Health campaigners said visiting a GP at the first sign of any symptoms could save a smoker's life.

Lack of concern

Forty-two per cent of respondents to the poll said they were not concerned about the effects of smoking on their health.

Sixteen per cent said they did not tell their doctor they smoked.

Most of those who would own up said they lied about the number of cigarettes they smoked each day.

Sixty-five per cent said they had considered giving up because of health concerns.

Tellingly, 58% said they were worried about the costs of cigarettes, which went up by 17p in Tuesday's Budget.

Those aged between 16 and 34 were more likely to consider quitting than their elders.

Nick Young, chief executive of Macmillan Cancer Relief, said: "The best thing you can do for your health is to give up smoking.

"Recognising the symptoms of lung cancer and visiting your GP earlier may help to save your life," he said.

Malignant disease

Lung cancer is the most common cancer affecting men and the second commonest affecting women - after breast cancer - in the UK.

More than 40,000 cases are diagnosed every year.

A cough is a common symptom and is likely to occur when a tumour grows and blocks an air passage. Another symptom is a constant ache in the chest which may be related to coughing.

Other symptoms may include shortness of breath, repeated pneumonia or bronchitis, coughing up blood, hoarseness and swelling of the neck and face.

In addition, there may be symptoms which do not seem to be at all related to the lungs. These may be caused by the spread of lung cancer to other parts of the body.

Depending on which organs are affected, they can include headache, weakness, pain, bone fractures, bleeding or blood clots.

Symptoms may also be caused by hormones produced by lung cancer cells.

One hormone causes a sharp drop in the level of salt (sodium) in the body. This can lead to mental confusion and even a coma.

Like all tumours, lung cancer can also cause fatigue, loss of appetite and loss of weight.