Gordon Brown has said "major efficiencies" are required from Whitehall departments so frontline services can be maintained.

Appearing before the Commons liaison committee, the prime minister also said asset sales will help to fund spending priorities.

He was pressed on the issue by Conservative MP Edward Leigh, who said the government faces "difficult choices" on spending.

The public accounts committee chairman said there should be "an open debate now about what we intend to do with our public services".

Brown told the senior MPs that his first priority is that "we have got to get back to growth and back to employment in the economy".

The "additional money" being spent now will help to create growth, he said.

Leigh noted newspaper reports that Whitehall is already planning for major cuts, and said it would be "disastrous for the civil service if there is no proper planning done now".

Brown said reports of planned 20 per cent cuts were "quite ridiculous".

He defended the decision not to hold a spending review before the next election, citing uncertainty about the direction of the economy.

"There may be more certainty later, but not now," said the prime minister.

But Brown acknowledged that Whitehall faces much tighter spending in the years to come.

"The profile of public spending will be different in the years to come and there are tough choices that have got to be made," he said.

"Yes, there are tough choices to be made. The profile of capital spending, for example, is going to be different in years to come."

Brown said asset sales would raise some revenue but the government would also seek "major efficiencies" from departments.

"Backroom services can save money so we can spend money on frontline services," he said. "We are determined to get money to the frontline services."

But Leigh warned: "You can't say everything can be met by efficiency savings."