Britain's "devastating" epidemic of obesity could threaten the very existence of the NHS, a report warns today.

Britain's "devastating" epidemic of obesity could threaten the very existence of the NHS, a report warns today.

Rising rates of heart disease, weight-related diabetes, cancer and other diseases threaten to cripple the health service and leave a generation of children who will die younger than their parents, the Commons Health Select Committee concluded.

John Reid, the Secretary of State for Health, yesterday postponed the Government's White Paper on public health until the Autumn following withering criticism of ministers for failing to take tougher action.

It accused Tessa Jowell, the Secretary of State for Culture, of being "naïve" and "espousing an idealistic and ill thought-through notion'' of backing the promotion of healthy foods rather than controls on advertising aimed at persuading children to eat unhealthy snacks.

The public health White Paper, which was to be published in July, will be used by Downing Street to test whether the Government will gain public support for tougher curbs, or be condemned for bringing in the "nanny state''. One Whitehall official said: "Ministers are not sure whether the public want to hear the Government saying it will ban advertising aimed at kids. We think the answer now is 'no' but they will put that to the test."

Mr Reid and Ms Jowell presented a united front yesterday to patch over their differences over demands for tougher controls on promotion of unhealthy snacks targeted at children. Advisers for the ministers insisted that they were "united'' in seeking a tougher voluntary code but would hold in reserve the threat of a ban on television advertising of fattening foods targeted at children.The 120-page report says the Government has failed to recognise the scale of the problem has not done enough to reduce and prevent the nation's expanding girth. It says that obesity could overtake smoking as the greatest cause of premature death.

An audit by the committee found that obesity and weight problems already cost the economy more than £7bn a year. David Hinchliffe, a Labour MP and chairman of the committee, said: "Our inquiry is a wake-up call for the Government. If the very existence of the NHS in its present form is threatened by costs spiralling totally out of control, it is hard to see that the Government will not, ultimately, be forced to intervene."

It too did not recommend a total ban on advertising of junk food to children - £178m was spent on advertising chocolate, sweets, crisps and snacks in 2002 - and ignored demands from for a "fat tax". Instead, as reported on Saturday by The Independent, it wants a voluntary ban on marketing to children but said legislation should be enacted if the industry had failed to rein in its advertising practices after three years.

Two thirds of adults and one-in-four children are overweight or obese, an increase of 400 per cent since 1980. If the trends continue, more than half of all children will have a weight problem by 2020.Energy intakes have fallen by 750 kcals a day over the past 20 years, but activity levels have fallen more, by 800 kcals. "Out of this small imbalance has come the wave of obesity," says the report.