�13bn has already been earmarked for health

On Saturday a leaked memo, drawn up by the prime minister's polling expert, warned that some Labour voters were disillusioned with the government's progress on health, education and law and order.

Departments covering those areas are tipped to be the major beneficiaries of Mr Brown's plans, along with transport, welfare and the New Deal.

But in return for the extra expenditure, Whitehall departments will have to agree to stringent conditions to raise the standards of the worst hospitals and education authorities, according to "informed sources" quoted in the paper.

The additional spending would allow ministers to reassure voters, in the run-up to the general election, that significant improvements to public services were in the pipeline.

At the same time, Labour will be anxious that the City is not left with the feeling that the government is loosening its tight control on public spending.

Ministers will argue that the new spending will not take Mr Brown outside the Budget framework, which foresaw a growth of 2.5% in current spending and a doubling of capital investment.

A Whitehall source has described the �28bn figure for extra spending as "speculative".