The chancellor, Gordon Brown, yesterday challenged other developed countries to join Britain and Italy in a project he said could save more than five million lives.

Mr Brown was speaking in Rome at the launch of a pilot scheme to supply developing nations with vaccines that are commonplace in the developed world. So far, only Canada, Norway and Russia have made firm commitments to the so-called Advance Market Commitments (AMC) project, which aims to make a vaccine for pneumococcal disease available.

The chancellor said the fact children died every day from avoidable diseases "touches the deepest places of conscience". He appealed to "other governments to put finance at the service of innovative medicine".

Mr Brown and other promoters of the scheme earlier met Pope Benedict, an enthusiastic supporter of AMCs. The chancellor, who is the son of a Church of Scotland minister, presented the pontiff with a published collection of his father's sermons.

Pneumococcal disease is the leading cause of 1.9 million child deaths each year from pneumonia. It is also the second most common reason for childhood meningitis deaths. A vaccine exists, but it currently takes between 15 and 20 years for new vaccines to become widely available at affordable prices in the developing world.

AMCs aim to eliminate the delay by providing manufacturers with a guarantee of future purchases of the vaccine in the developing world, provided a market can be shown to exist and an affordable long-term price agreed. The pilot scheme aims to secure the immunisation of 70-100 million children by 2020, by which time it is estimated that up to 700,000 lives will have been saved.