Microsoft founder Bill Gates says his foundation and other donors will be announcing nearly $4bn of new funding aimed at reducing the number of deaths from malaria.
After two decades of decline the disease is again becoming more common as mosquitoes develop resistance to existing medication.
Gates spoke as campaigners and health groups gathered for a major malaria summit in London.
He said he wanted his money to improve the bed-nets used to help combat the spread of the disease and refine the mapping of where they should be located.
Gates said the ultimate aim would be to wipe out malaria and find a long-lasting vaccine.