Some of the world's richest countries, led by the UK, have pledged $4.3 billion to the GAVI Alliance to help vaccinate children in developing countries against common but deadly diseases, $600 million more than had been expected.

The commitments were made at a pledging conference in London and brings GAVI’s total available resources for 2011-2015 to $7.6 billion. The UK is giving an extra $1.34 billion, bringing its total contribution to GAVI to$2.45 billion, while the Bill and Melinda Gates Foundation has pledged a further $1 billion.

Other significant donations are coming from Norway ($677 million) and the USA ($450 million). Australia is pledging $149 million.

Aside from the UK, the donations from other European countries are considerably lower. Sweden, the Netherlands and France are giving significant sums ($201 million, $175 million and $146 million, respectively), though  Germany has pledged $73 million. Italy will donate just $25 million, while Russia and Spain are not contributing anything to this round of funding.

Prime Minister David Cameron said that GAVI was "one of the very top performers in our root-and-branch review of the agencies that deliver British aid because it demonstrates tangible results". He added that the UK's support "will help vaccinate over 80 million children and save 1.4 million lives. That’s one child vaccinated every two seconds for five years".

Bill Gates said his foundation was pleased to work with donors "who understand that buying vaccines saves lives, and who know it is an investment worth making, no matter how tight their budgets".