Between 15,000 and 20,000 jobs could be axed in the NHS because of the cash crisis facing the service, the Conservatives are predicting.
More than 4,000 job cuts have been announced over the past few weeks
They base their figures on reports that one in three hospitals are in debt, with many laying off 10% of staff.
Over the last few weeks hospital trusts across England have announced more than 4,000 job losses as they struggle to balance their books.
Health Secretary Patricia Hewitt said the best care would be maintained.
Gordon Brown faced claims he had abandoned the NHS from opposition politicians and campaign groups for not helping the health service in Wednesday's Budget.
Within hours of delivering his financial plans for the coming year, it was announced that 480 jobs were to be axed at north London's Royal Free Hospital.
Then the major hospital trust serving Tony Blair's constituency, the County Durham and Darlington NHS Trust, said it was cutting 700 jobs over the next two years - even though it would break even this year.
And East Kent Hospitals NHS Trust said it would have to cut job to claw back a predicted £35m deficit for next year.
The Chancellor defended himself saying an extra £6 billion is being invested over the next two years in the NHS.
Health Secretary Patricia Hewitt has repeatedly claimed that only a minority of health trusts are in the red and that they can achieve financial balance over the next year if they work more efficiently.
Responding to the Tory claims she said most NHS hospitals, including those with deficits, were improving patient care and hitting targets within budgets.
"Over the last 9 years the NHS has taken on over 200,000 more staff.
"Even where trusts are now making some reductions - starting with agency staff, managers and administrators - patients should be reassured by the determination of clinicians and management to maintain the best care for patients," Ms Hewitt added.
But Shadow Health Secretary Andrew Lansley said deficits in the NHS in England now topped £750 million and accused the government of mismanaging the service.
"Much of the money it has pumped in has been wasted by bureaucracy or the mismatch of supply and demand," he said.
He added that the laying off of such a huge number of doctors and nurses was absurd.
Former health secretary Frank Dobson said the main cause of deficits, cuts, closures, job losses and reductions in patient care in the NHS was the latest round of re-organisation.
He called for the government to suspend its reform plans in order to prevent further financial problems.
Nigel Edwards, director of policy at the NHS Confederation which represents over 90 per cent of NHS organisations, said some hospitals had had to make tough decisions in recent weeks.
He said there were two main reasons for the job loses.
Some had been necessary to balance the books and others had been because trusts had decided they could do things more efficiently by providing care outside hospitals, he added.
The past two weeks have been characterised by successive job cut announcements:
North Staffordshire NHS Trust said it was axing 1,000 jobs to battle a £30m deficit for next year - 750 of which would be compulsory.
Wolverhampton's New Cross Hospital also said it was expecting to make 300 job cuts to help tackle a £38m deficit
The Royal Cornwall Hospitals NHS Trust which is expecting an £8.1m deficit for this year announced 300 job losses
Some 200 job cuts are predicted both at Plymouth Hospitals NHS Trust and at St Mary's Hospital in Sidcup, Kent
Shrewsbury and Telford NHS Trust is predicting 300 job cuts
Peterborough and Stamford NHS Trust wants to cut 185 jobs and
90 jobs are expected to be axed at Kingston primary care trust in Surrey
NHS Direct is also predicting losses to the tune of 400 jobs