Hospital job cuts could reach 24,000 - four times the number of job losses announced in recent weeks - the Liberal Democrats have claimed.
More than 6,000 job have been cut in hospitals in recent weeks
The Lib Dems said the 6,000 job cuts announced in recent weeks accounted for only a quarter of the total NHS deficit.
Lib Dem health spokesman Steve Webb said the government refused to "come clean" about the crisis in the NHS.
However, the Department of Health and NHS bosses dispute the Lib Dem figures.
Thousands of job losses have been announced in recent weeks as trusts battle financial difficulties.
"Every day brings further news of more job cuts which will undoubtedly affect frontline patient care," Mr Webb said.
"Staff morale and public confidence in the NHS will continue to crumble until ministers take action to reverse this trend."
The Lib Dem health spokesman claimed taxpayers' money was being wasted on health reforms and paying over-the-odds for private sector treatment to hit waiting list targets.
And he argued that trusts were being forced to make short-term cuts to tackle problems that have built up over decades.
Mr Webb said: "What is needed is long-term planning in the NHS, not a series of short-term initiatives and sudden policy shifts which make sensible planning impossible."
Professor Allyson Pollock, a professor of public health policy at the University of Edinburgh and a supporter of pressure group Keep our NHS public, criticised the funding of hospitals.
She told the BBC that many of the problems were caused by money "leaking out of the whole of the NHS into very expensive for-profit contracts in the private sector".
A Department of Health spokesperson said: "These are crude calculations. It is simply not correct to say that thousands of jobs will be lost within weeks, as some reports would have it.
"Most trusts in the news say that they expect most reductions to be achieved through 'natural wastage' - not replacing temporary or agency staff, freezing non-essential vacant posts and redeploying staff into other roles.
"In most cases trusts are planning to make reductions over a period of years."
Dr Gill Morgan, chief executive of the NHS Confederation, said it was not possible to project in the way that the Lib Dems had done.
She said: "Some hospitals have had to make very difficult decisions in recent weeks and unfortunately some job losses have been necessary.
"It is possible that there will be more job losses announced in the NHS, but the actual figures cannot be calculated in such a simplistic way as there are many reasons for the cuts.
"It is spurious to take data from a few trusts and extrapolate national figures."