The Scottish Government was under intense pressure to say how it will pay for its pre-election promises last night after a leaked document suggested key pledges will have to be ditched in order to pay for a freeze in council tax.

A finance report for Cosla, the local government umbrella body, revealed that SNP ministers are willing to fund councils to the tune of just less than £12bn by 2010-11.

Council leaders say that will be enough to cover the estimated £420m it will cost to freeze council tax bills at current levels for the next three years.

However, they warn that it will only leave an extra £175m - not enough to pay for SNP manifesto promises such as boosting police numbers and increasing the number of free nursery places by 50%.

The document also indicates councils do not believe there will be additional money available to reduce class sizes to a maximum of 18 in P1 to P3 or to fund the increase in free personal care payments announced by Nicola Sturgeon, the Health Secretary.

The Scottish Government wants to freeze council tax as a prelude to scrapping the charge and replacing it with a local income tax.

John Swinney, Finance Secretary, announced yesterday the government will publish a consultation document in the next few weeks.

Andy Kerr, Labour's Shadow Finance Secretary, said the Cosla document showed the SNP was ready to drop its election promises in order to "bully councils into freezing council tax".

"Many people who voted SNP did so because of pledges such as extra police and smaller class sizes," he said. "The SNP are prepared to betray all those people."

The Cosla finance report was obtained by the Labour Party in advance of a meeting today at which council leaders will discuss the government's budget proposals.

Council leaders are understood to be furious the document was passed to Labour.

A senior source told The Herald: "We're outraged the Labour Party nationally has used a leaked document for party political benefit over the benefit of local government."

John Swinney has held a series of meetings with councils in order to strike a deal on the local government funding settlement before he delivers his Budget speech to the Scottish Parliament on Wednesday.

According to the leaked report, councils will receive just in excess of £11.1bn in 2008-09, an increase of £500m from the 2007-08 figure.

Local authority funding will then rise to £11.6bn in 2009-10 and £11.9bn in 2010-11.

However, once inflation and the money required to freeze council tax are taken into account, the Cosla document says councils will only have an extra £38m to spend in 2008-09, £101m the following year and £36m the year after that.

A separate table contained within the report suggests that will enable them to spend £22.5m on recruiting police officers, £55m less than the SNP estimated was needed.

It also says councils will have £42m to increase nursery places - £123m less than required - and £40m to introduce free school meals, £100m less than the original estimate.

A senior SNP source said: "All John Swinney is focusing on right now is talking to Cosla and he won't be distracted.

"Hopefully, the parties can agree on a satisfactory outcome for all."