The National Blood Service (NBS), which runs transfusion centres, warned that another cold spell or a sudden demand on the blood stocks could have serious consequences, including the cancelling of operations. At present supplies of blood are at 12,000 units, which is more than half the maximum stock reached before Christmas.
Peter Gibson, NBS spokesman for London and the South-east, said this year was unique because of the combination of a severe weather spell and a major flu outbreak. "There has been a 50 per cent drop in supplies in three weeks. The severe weather meant sessions were cancelled, pipes burst, vans got stuck and demand just jumped within two to three days."
Transfusion centres in London and the South-east, which supply 40 per cent of the national blood supply, were yesterday down to a third of their usual supply of the most common group - O positive.
"If it doesn't pick up there is potential disaster," he said. "It is really important that hospitals don't close. People only respond when there is a problem, but every year hospitals need more blood."
Only 5 per cent of potential donors give blood, although before Christmas the NBS registered the highest ever blood stock at 25,000 units in the wake of major advertising. The London campaign featured a seven-year-old boy who had undergone 22 operations in the past two years.
The National Blood Authority, which overseas the distribution of blood across the country, yesterday denied that the situation was critical. "The position is tight. More people are needed to come forward," said a spokeswoman. "But we are not at that stage yet. We are managing to keep up and we are meeting hospital demand."
When the service was controversially re-organised by the government nearly two years ago, blood chiefs predicted there would be no shortages. But this is the second winter when blood has almost run out.
Last year the NBA was plunged into crisis when stocks of blood reached an all time low of just over 8,000 units. The NBA says stocks of blood are always low in January, but transfusion service staff believe the current situation is one of the worst ever.
The problem was exacerbated by an oversight which allowed 1,000 units of blood to be left in an Essex blood bank for three weeks waiting to be tested.
Last night a member of staff at the Brentwood Transfusion Centre in Essex said: "It's a disgrace. Blood only has a shelf life of 35 days."
The NBS has to cope with marked fluctuations in blood donations. Last month, it said stocks had fallen so low in London and the South-east that there was only just over half a day's supply left.
The service was forced to restrict blood orders to hospitals to the minimum possible and issue a warning that some non-emergency operations could be cancelled.
Similar problems were reported last month in Scotland where blood supplies ran desperately low as hospitals dealt with the E. coli 0157 outbreak.
The National Blood Authority can be contacted on 0345 711711.Reuse content