The BBC's Charles Rhodes: "The bug is gathering pace"

The number of those catching the bug has risen by more than 80% in just seven days and hospitals and ambulance services are bracing themselves for a further tide of emergency admissions and deaths .

Provisional figures released on Wednesday by the Royal College of General Practitioners (RCGP) showed the first large rise in cases in the south as the virus spreads from the North and the Midlands.

The survey of family doctors by the RCGP's Birmingham-based flu monitoring unit found more than 97,000 people in England and Wales had fallen last week, compared with about 53,200 in the previous week.

'It's not an epidemic'

Flu experts continued to stress that the outbreak was nowhere near epidemic proportions, with the numbers of ill people at the same level as the last normal outbreak in the winter of 1996-97.

Dr Alan Hay of the World Health Organisation Influenza Centre in north London, which has been monitoring the evolution of flu for more than 50 years, said there was no evidence of an epidemic.

He said: "I guess there was very little flu around and then it has started to increase very rapildy, probably at a rather inconvenient time of the year when everyone wanted to go to parties.

"So that may make the impact appear somewhat greater but in fact the curve that one plots for what's happened so far this year compared relative to what happened two years ago is very similar."

Nevertheless the young and elderly are falling ill in increasing numbers as the so-called Sydney flu strain reaches the height of its five-week cycle.

"In most influenza outbreaks there is a rising incidence over about five weeks before it falls," said Dr Douglas Fleming, director of the RCGP influenza monitoring unit. "On that basis, peak incidence is likely to occur in many areas during this week."

Second standby mortuary

As the Emergency Bed Service issued a warning that hospitals may run out of beds, it emerged on Wednesday that a second Norfolk hospital is using a refrigerated lorry trailer to act as a standby mortuary.

Managers at the James Paget Hospital in Gorleston, near Great Yarmouth, brought in the unit, similar to one in use at the Norfolk and Norwich Hospital, after their 50-space morgue began to run out of space.

"The unit has been brought in as a contingency," said a spokeswoman."We are not using it at this stage, but the next few days will prove crucial - if we can get through that then hopefully it will be all right."

The grim prospect of an overflow morgue arose because of a combination of the Christmas holiday shutdown in the funeral industry and a rise of up to 50% in flu-like illnesses and cases of pneumonia, the hospital said.