Genetically-modified mosquitoes that are resistant to a malaria parasite may one day stop the spread of the disease, a new US study says.

In research published online in the Proceedings of the National Academy of Sciences, scientists describe how the genetically-modified, or GM, mosquitoes outbred natural mosquitoes when fed mouse blood infected with a malaria parasite.

The scientists at Johns Hopkins University combined equal numbers of genetically modified and natural mosquitoes in the laboratory and let them feed on malaria-infected mice.

The genetically-altered insects survived in greater numbers and laid more eggs.

After nine generations, 70% of the mosquitoes were GM ones compared with 50% at the outset of the experiment, Professor Marcelo Jacobs-Lorena and his colleagues write.