A US biotechnology company has been giving details of a vaccine against Aids, which it hopes could be available by 2005, to delegates attending the International Aids Conference in Barcelona.

The head of VaxGen, Donald Francis, said the vaccine worked on chimpanzees and he was optimistic about the results of trials on humans, due to be published next year.

VaxGen’s vaccine will be part of the biggest-ever HIV vaccine trial due to begin later this year in Thailand with the involvement of 16,000 people.

Reports of scientific progress were accompanied by warnings that rich nations needed to spend more to help bring the epidemic under control.

Malaysian activist Irene Fernandez told the conference that North American and European countries were not meeting their targets for foreign aid set by the Organisation for Economic Co-operation and Development (OECD).

If they did, she said, there would be enough money to fund Aids-prevention programmes.

The six-day conference is organised by the United Nations agency UNAids and is being attended by 15,000 delegates.