Gordon Brown's plan to increase funding for immunisation against killer diseases in poor countries received a boost yesterday when Europe's statistical body ruled that the scheme would not count as government borrowing.

Mr Brown is trying to launch an international finance facility for immunisation (IFFIM) project that would raise up to $4bn (£2.25bn) over the next 10 years to fund programmes, mainly in Africa, that could save 5 million lives.

The decision by Eurostat and Britain's Office for National Statistics means the bonds issued to raise money for the vaccination programmes would be scored to a new international organisation rather than to individual governments.

This is important because many European governments, some already running large public deficits, have balked at taking on more borrowing.

The Treasury described the move as a "major step forward" which would enable it to get the IFFIM up and running as soon as possible. "Crucially this innovative new financing mechanism will frontload additional aid and provide it on a secure, predictable footing, maximising the impact," said a spokesman.

The UK will provide a third of the resources required for the scheme. France, Italy, Spain and Sweden have said they will contribute and the Treasury said it hoped for further pledges in the near future.

The IFFIM has been developed and supported by the Bill and Melinda Gates Foundation, the World Health Organisation, the World Bank and the Vaccine Fund, which collectively form the Global Alliance for Vaccines and Immunisation.

Mr Brown remains hopeful that the idea can be widened to increase overseas development aid more generally but his idea has run into opposition from some countries, in particularAmerica. The US says its laws make it difficult to back the facility but has urged other countries to go ahead with it if they wish.