Ministers are discussing these drastic measures to try to reverse the trend towards sedentary lifestyles, lack of physical activity and consumption of junk food. The success of 'get fit' fiscal incentives in Scandinavian countries is being closely scrutinise to see if they might work in Britain.

The proposals were floated earlier this month at the inaugural meeting of the Activity Co-ordination Team (ACT), a new group of Ministers, advisers and senior civil servants focusing on a public health risk that is as serious as smoking.

Businesses could be given tax allowances if they instal a gymnasium; contribute to employees' gym memberships; replace their snack machines with water dispensers; and phase in healthier food in canteens.

The ACT, chaired by Sports Minister Dick Caborn and Public Health Minister Melanie Johnson, is drawing up an action plan to tackle an explosion in health problems related to inactivity, such as heart attacks and diabetes.

Physical inactivity costs the country £2 billion a year and contributes to 54,000 premature deaths. Sir Liam Donaldson, the Chief Medical Officer, has called it and the related epidemic of obesity 'a health timebomb'.

Roger Draper, the chief executive of Sport England, and a member of the ACT, said: 'If people can show that they are saving the NHS money by going to the gym, swimming or walking, then we have to come up with a range of incentives, including fiscal incentives, to reward their effort. Even a small increase in the number of people taking regular exercise could save the NHS millions, increase productivity levels, reduce absenteeism and promote general well-being.'

The group is aware that monitoring people's particpation in activities would be difficult.

One idea is to ask gyms for their members' attendance records.

Another is that overweight people who visit their GP with a problem related to their size could then agree to undertake an agreed amount of exercise. Their visits to a sports centre could be kept and, if targets are met, a tax break given.

In Finland, where there's an 'exercise' tax break, 70 per cent of the population take 30 minutes of exercise five times a week.

In England it is just 32 per cent and most of that is from doing manual labour rather than playing sport.

Ministers are also considering either cheap or free entry cards for local sports centres to those who do little exercise, such as the poor, those out of work and the unemployed.

The Department of Health is coming under pressure to increase the £710,000 it spends of its £61.3bn annual budget on promoting activity.