The World Health Organisation is now pushing for a pesticide that is banned in the developed world to be used once again in the fight against malaria in Africa.

DDT was banned 30 years ago because it accumulates in the fat cells of non-target species and becomes more concentrated as it moves up the food chain. That means it is particularly dangerous to predators such as lions, leopards and humans, and to birds of prey.

Eggshells are extremely vulnerable and populations of several species, including the Peregrine Falcon, plummeted when the pesticide was in wide use.

DDT, however, is extremely effective in controlling malaria-carrying mosquitoes.

Many environmentalists fear the polluting effects of the chemical will spread, although the WHO says spraying should be limited to the insides of houses and their roofs.

Arata Kochi, the new head of the WHO's malaria programme, has made no secret of his determination to bring back the chemical weapon that helped rid Europe and the former Soviet Union of malaria decades ago. "We must take a position based on the science and the data. One of the best tools we have against malaria is indoor residual house spraying. Of the dozen insecticides WHO has approved as safe for house spraying, the most effective is DDT."

The WHO called on all development agencies and governments to incorporate the use of DDT in malaria control programmes and to issue statements on where they intended to use it and how they would manage it. WHO promoted the use of DDT in the 1970s and said that, as a result, about 700 million people were no longer at risk.

The WHO says: "The burden of malaria that remains today, much of which is in sub-Saharan Africa and in remote rural areas of Asia and Latin America or among marginalised populations, is unacceptably high."

However, Barbara Dinham, of the Pesticide Action Network, said that a return to the use of DDT could increase incidences of many other life threatening problems including cancer.