Britain's hospitals are facing a winter crisis similar to that of two years ago when the NHS came close to collapse, senior doctors have warned.

Thousands of patients face repeatedly cancelled operations despite increased investment by the Government in nurses and beds.

In the winter of 1999-2000, the NHS almost ground to a complete halt because of an outbreak of flu. Almost all non-emergency operations were cancelled, and the country at one point was left with just two intensive-care beds, with patients shuttled hundreds of miles in search of somewhere to stay.

The crisis was so severe it destroyed public faith in the NHS, and forced Tony Blair to launch a national plan to save it. A similar crisis was avoided last year only because the incidence of flu was unusually mild.

However, doctors are convinced that the NHS is heading for a repeat of the earlier crisis. Jonathan Fielden, clinical director for emergency services at Royal Berkshire & Battle Hospital, said: 'This year we are more concerned - hospitals are already in perpetual crisis, even during the summer, and there are reports the Sydney flu might hit us. I think it likely the crisis will be as bad as two years ago.'

Intensive-care beds in the country should be running at less than 85 per cent occupancy, but most hospitals are running at over 90 per cent occupancy. In some cases, intensive-care units are running at over 100 per cent, averaging more than one patient in each bed every day.

An Audit Commission report last week showed that Accident and Emergency wards have been deteriorating rapidly over the last few years. Far more people have to wait more than four hours to see a doctor than two years ago.

'We are running flat out already; there is no spare capacity. Even if we have just an averagely bad winter, we will be in for trouble. There will be a lot of patients having their operations cancelled,' said Dr Peter Hawker, chairman of the British Medical Association's Central Consultants' Committee.