Britain's public finances fell back into the red in May, showing a deficit of �2.6bn ($3.9bn; 4bn euros).

The deficit - the first this year - is a signal that the government is starting to borrow to finance its spending commitments.

Many analysts had expected that the deficit could be as high as �3.6bn this month, but a higher-than-expected tax take contributed to a lower deficit.

John Butler, an economist at HSBC, said: "The fact receipts are holding up is a reflection that people are still in jobs and we haven't slowed down as much as maybe the GDP (gross domestic product) numbers suggest."

In April, there had been a �3bn surplus, highlighting the erratic nature of the figures. Spending and tax receipts vary from month to month.

In the financial year to date, a surplus of �300m has been recorded.

The big boost in government spending over the next few years - announced by Gordon Brown in the Budget in May - is designed to ensure that the government meets its pledge to improve the public services over the life of the Parliament.

Mr Brown has already announced a huge increase in health spending, and details of other spending plans will be revealed in July when the government publishes its comprehensive spending review.

The increased government spending is also designed to provide a boost to the economy which has been suffering from the delayed effects of the slowdown in the world economy.

Official figures show that UK GDP did not grow at all in the six months between October last year and March this year.

The scale of government borrowing could also influence the Bank of England in its deliberations on whether to raise interest rates.

A faster than expected increase in the deficit could add to pressures to raise rates to curb inflation - although the higher than expected tax receipts show that the economy is showing some signs of recovery.