The Treasury said it was on target to keep high-profile pledges for more aid to the developing world, but the promise came at the cost of funnelling some money through ministries other than the department for international development (DfID).

DfID received an 11 per cent annual average rise in real-terms aid over the next three years – much higher than for government spending as a whole. But overall overseas aid is set to rise by 17 per cent a year over three years, with big increases also being pushed through the department for the environment, food and rural affairs (Defra), the foreign and commonwealth office (FCO) and the ministry of defence (MoD). The increase is backloaded disproportionately into the third year of the spending round.

Two new pots of money – an “environmental transformation fund” and a “stabilisation aid fund” to help peacekeeping and reconstruction in post-conflict countries – will be shared jointly between DfID and the other departments.

Aid campaigners said the move appeared to be a compromise between putting all the money into DfID, which might have aroused resentment and envy elsewhere, and channelling the money through departments like Defra that have little experience in spending development aid. They had initially believed that Defra, the FCO and the MoD would scoop much more of the extra funding.

”We welcome the fact that this is moving the UK in the right direction in terms of keeping its promises,” said Patrick Watt, policy coordinator at Action Aid. “But it is fortunate that it does not signal too big an increase in aid outside DfID”.

The Treasury’s plans mean the UK will hit a target agreed by European Union member states in 2005 in the run-up to the Group of Eight rich countries’ summit in Gleneagles, Scotland, of giving aid equivalent to 0.56 per cent of national income by 2010. The UK has further pledged to hit the longstanding United Nations target of 0.7 per cent of national income in aid by 2013.

The UK is expected to spend just 0.37 per cent of national income in aid in 2007-8, lower than projected, though this figure is distorted by the large amounts of debt relief given to Nigeria in 2006. The Treasury and DfID have been embroiled in an argument with development campaigners about how much debt relief should be counted as aid, but there appear to be few big debt write-offs on the horizon that could distort aid numbers over the next three years.