Eliminating malaria in many parts of the world where risk of the disease is high may be less difficult than previously thought, international researchers said on Tuesday.

They found that in many areas transmission rates are below the level at which controlling the disease with things such as bed nets is a real possibility, Simon Hay of Oxford University in Britain, who led the study, said.

"In Africa, surprisingly, we found that about half the 660 million people at risk live in areas where technically you should be able to have a very substantial impact and could bring transmission down to near zero," Hay said in a telephone interview.

"The map is a resource you need to prepare proper antimalarial control and elimination."

Malaria is one of the deadliest diseases worldwide, killing 880,000 people each year, mostly children under age five in sub-Saharan Africa.

A parasite transmitted by mosquitoes causes the disease, which has become resistant to some drugs. At the same time work on a vaccine has been slow.

But the findings published in the Public Library of Science journal PLoS Medicine suggest that control efforts such as bed nets could cut transmission rates to near zero for many people in high-risk areas around the world, especially Africa.

The map showed that more than half of the people at risk in Africa -- about 350 million people -- live in areas where transmission rates are below 40 percent. This is the cut-off at which it is technically possible to eliminate and control the disease.

The findings also show that the biggest challenge for health officials is in the western and central parts of sub-Saharan Africa, where transmission rates are above this level, Hay added.

The researchers compiled medical statistics, climate data and a large archive of community-based estimates of parasite prevalence.

They plan to update the map annually to create an ongoing record of malaria control and elimination efforts and a guide that points to where investment is needed, Hay added.

"As time goes on we will be able to track where we are doing a good job and where we are not doing so well in targeting malaria," Hay said.

(Reporting by Michael Kahn, Editing by Maggie Fox and Dominic Evans)