Lack of political and financial support on the part of donors means that endemic countries are often encouraged to 'leave alone' failing malaria, and are not given financial and technical help to implement more effective strategies.

Malaria, already responsible for at least a fifth of all deaths of children under five in Africa, will continue to increase its hold on the continent unless Britain and the US provide more effective, but more expensive, medicines, it was claimed yesterday. Médecins sans Frontières, whose volunteer doctors run clinics in malarial areas, called on the Department for International Development and the US government agency USAid to stop their "go-slow" policy on malaria. This focuses on prevention of mosquito bites by means of bednets and treatment with traditional drugs.

"Donors must stop wasting their money funding drugs that don't work," MSF said in a report. It called on Britain and the US to help African countries to introduce combinations of drugs which include artemisinin, a treatment derived from a Chinese plant which has proved extremely effective in Asia.

MSF points out that the World Health Organisation has recommended that artemisinin-based combination therapy (ACT) be introduced wherever resistance to the old drugs is high.

"Lack of political and financial support on the part of donors means that endemic countries are often encouraged to 'leave alone' failing malaria, and are not given financial and technical help to implement more effective strategies," the report says.

Resistance to chloroquine, once the drug of choice for malaria, is more than 90% in some parts of west Africa. Resistance to its replacement, sulfadoxine-pyrimethamine, is fast growing, particularly in east and southern Africa. MSF made its plea for action as the WHO and Unicef launched a report on the malaria crisis.

Deaths in west Africa remain high, according to the WHO, while "the number of children dying of malaria rose substantially in eastern and southern Africa during the first half of the past decade compared with the 1980s".

That did not mean efforts to combat malaria, through the WHO's Roll Back Malaria programme, had failed, it said - the situation might be substantially worse without them. The WHO report noted that despite its recommendation, use of ACT "is constrained by high costs and limited operational experience in Africa.

To date, four African countries have adopted ACT as first-line treatment." There is greater use of bednets than ever before, but only 15% of young children sleep under them and just 2% of the nets are impregnated with insecticide. Although the price of the treated nets has fallen, some African countries have failed to lift taxes on them.

The campaigning organisation Massive Effort said yesterday that only 17 out of 43 countries that signed a declaration on malaria three years ago had fulfilled a promise to remove the tax. The organisation also accuses the World Bank of failing to deliver on funding it promised to combat malaria.

Since it undertook to provide up to $500m (£310m) in additional funds, it has been spending at the rate of just $44m a year, according to campaigners.