Britain and billionaire Bill Gates pledged $2.3 billion at an international donor conference on Monday to fund vaccination programmes to protect children in poor countries against diseases like diarrhoea and pneumonia.

The money adds to a pledge made by Australia's Foreign Minister Kevin Rudd on Sunday who said his country would donate $210 million to GAVI over three years until 2013.   

More international donors, including the United States, France, Germany, Japan and others, are expected to add their pledges later on Monday in an effort to stump up an extra $3.7 billion needed by the Global Alliance for Vaccines and Immunisation (GAVI) to fund its programmes though to 2015.

"Britain will play its full part. In addition to our existing support for GAVI, we will provide 814 million pounds of new funding up to 2015," Cameron said to applause as he opened the conference.

"This will help vaccinate over 80 million children and save 1.4 million lives."    

Billionaire philanthropist Gates, one of GAVI's major backers who helped set up the alliance more than a decade ago, also announced additional funding.

"Our foundation wants to do its part so I'm pleased to announce to you that we are pledging an additional billion dollars," Gates said, adding the money would be spread over the next five years.

GAVI says it has helped prevent more than 5 million child deaths in the last decade with its immunisation programmes and will prevent 4 million more by 2015 with the necessary funds.   

The alliance funds bulk-buys of childhood vaccines against diseases such as pneumococcal pneumonia, Haemophilus influenzae type b, or Hib disease, diphtheria, pertussis or whooping cough, tetanus, measles and rotavirus.   

The World Health Organisation says it considers vaccination as "one of the most successful and cost-effective public health interventions". It estimates that between two and three million deaths are averted each year through immunisation.   

A series of academic studies published last week found that if 90 percent of children in the more than 70 poor countries supported by GAVI were fully immunised, some 6.4 million children's lives and more than $151 billion in treatment costs and lost productivity could be saved over 10 years, producing economic benefits of $231 billion. - Reuters