Government departments face billions of pounds of cuts, including £4.35bn from the health budget in England.

Ministers had already announced plans to make £11bn "efficiency savings" by 2013 but departments have been spelling out how cuts will be achieved.

They say savings can be made by moving civil servants out of London, reducing staff sickness and use of consultants.

The Lib Dems said it was "phoney", the Tories said it was a "bogus exercise" and did not identify all planned cuts.

Health faces the biggest cuts in spending, while the department for children, schools and families faces cuts of £1.1bn.

The government announced its intention to make £11bn savings by 2012-3 in the pre-Budget report, but on Wednesday - shortly after Chancellor Alistair Darling's Budget - different departments began announcing what their contribution would be.

Staff sickness

BBC political editor Nick Robinson said the "vast sums" were not included in Mr Darling's speech, nor the Treasury's "red book" but came out in press releases afterwards.

Other savings announced include £700m from the Ministry of Defence, £500m from the Department of Work and Pensions, £343m from the Ministry of Justice, £300m from the Department for Business and £194m from Defra.

The Department of Health said it would find savings in procurement, its national IT programme, energy efficiency and reducing staff sickness - something it said could save £555m.

"How do you make nurses not be ill"

Health Secretary Andy Burnham said that "tough efficiency savings" would allow his department to "continue to increase real-terms resources available for patient care year-by-year".

And Work and Pensions Secretary Yvette Cooper told the BBC: "There are a series of areas within the NHS budget where you can make additional savings, for example on IT and so on, whilst at the same time protecting the front line services - the doctors, the nurses."

But Lib Dem Treasury spokesman Vince Cable told the BBC: "What they are saying is this is all about efficiency, well if it's inefficient why have they put up with it for 10 years And how do you make nurses not be ill... It's a great aspiration but how on earth do you make these things happen

"It's largely phoney, it doesn't spell out honestly what the real choices are that have to be made in public spending."

'No substitute'

The Home Office says it will make £350m savings through "operational productivity" at the UK Border Agency, reducing consultants and spending on IT.

Home Secretary Alan Johnson told the BBC it would not mean fewer police on the streets: "All warranted officers and PCSOs, who are doing such a good job on neighbourhood policing, that's ring fenced."

The Conservatives said that without a spending review, ministers could not accurately measure any savings after 2011.

Shadow chief secretary to the Treasury Philip Hammond told the BBC the exercise was "no substitute for a proper comprehensive spending review" which would set out departments' spending totals over three years.

"What we do know is that the cuts we are talking about here which add up to about £11bn are about a third of the total cuts that are required over the period.

"There is another £20bn of cuts that have not been explained at all... We've got nowhere near to understanding where Labour will deliver these spending cuts. This is a bogus exercise."