Prime minister Tony Blairs promise to increase the share of national income spent on the NHS to European levels in five years has been attacked as a cynical ploy by financial analysts.

British Medical Association chair Dr Ian Bogle has already written to demand clarification of the governments precise intentions.

Mr Blair told BBC's Breakfast with Frost that his promise could be met through annual cash increases of about 5 per cent a year in real terms until 2006, at the end of a week in which the government came under sustained attack for its handling of the winter crisis.

Officials clarified the pledge as meaning that spending on health would be increased from 6.7 per cent of GDP now - of which 5.7 per cent goes on the NHS - to the European average of 8 per cent.

Mr Bogles letter effectively asks whether the government means to increase spending in real terms by 5 per cent for five years, or meet the GDP promise, or do whichever is greater.

John Appleby, director of the health systems programme at the Kings Fund, said the GDP pledge was based on out of date statistics from the Organisation for Economic Cooperation and Development and we cant assume the gap is the same as three years ago.

The Office of Health Economics said the GDP figures were a misleading, unweighted average. Associate director Jon Sussex said: Tony Blair is talking about 8 per cent, saying that is the average, but 8.7 per cent is the correct average according to most people.

Even reaching 8 per cent of GDP would not bring the UK up to the EU average, Mr Sussex added, because health spending is rising. By 2006 the target of average EU spending would be much higher than 8 per cent.

And Tom Jones, health spokesman for the Association of Chartered Certified Accountants, said: People have got stuck on this percentage of GDP and it doesnt mean anything.

Mr Jones said the GDP figures quoted by Mr Blair were crude comparisons when there is no real definition of GDP and it depends on the value of an economy .

Mr Jones said Britains spending per head on health is 28 per cent below the European average and the government would have to spend the equivalent of a 3p per head increase in income tax to close the gap.

NHS finance directors said extra money was needed without strings.

Healthcare Financial Management Association chair Barry Elliott said: A certain amount needs to go into the basic infrastructure that has deteriorated over the years because of funding squeezes.