Travellers in the US, UK and Germany could soon find themselves donating to the fight against Aids and malaria when they buy an airline ticket over the internet under a scheme to raise hundreds of millions of dollars for healthcare in poor countries.

The scheme, which may involve an automatic contribution with an opt-out, could be launched by May 2010 as a complement to an air ticket tax that has raised nearly $1bn since it was was launched in France and a handful of other countries three years ago.