There is little to show for the £21bn in annual NHS spending allocated to reduce health in-equalities, the Audit Commission has concluded.

The commission says that although outcomes have improved overall, extra funding given to the poorest areas has coincided with a widening in the health inequalities gap.

The commission says there is scant information about how much is actually spent on direct public health interventions

The NHS funding formula allocates £21bn of the £98bn NHS budget on the basis of health inequalities, the commission estimates.

This has resulted in “spearhead” primary care trusts receiving around £400 - or 24 per cent - per head above the England average.

But the commission’s managing director of health Andy McKeon said “most” of that £21bn was spent on tackling the consequences of health inequalities - such as higher hospital admissions - rather than the causes.

The commission’s report Healthy Balance also said that hospitals in poorer areas had higher costs that could not be explained by having more or sicker patients, which raises concerns that extra funding in poor areas has subsidised inefficiencies.

The commission says there is scant information about how much is actually spent on direct public health interventions.

The most widely used estimate is £3.7bn, or 4 per cent of health service spending.

But the commission found just £1.4bn of this - equivalent to £10m per primary care trust - is conducive to local flexibility and determination, raising questions over Conservative plans to ringfence the £3.7bn budget and put it under the shared control of councils and PCTs.

A Conservative spokesman confirmed the party was working to the £3.7bn figure, but he said the party hoped to collate more accurate data if it formed a government.

“We want properly accounted for ringfenced budgets that are actually spent on public health,” he said.