The fight to beat malaria in Africa is being hampered by poor quality and fraudulent drugs.

That is the view of researchers writing in the Malaria Journal who argue that unless urgent action is taken both within Africa and internationally, millions of lives could be put at risk. They note that medicines on sale in the continent have been deliberately counterfeited by criminals or are of poor quality resulting from factory errors.

Both types are not only potentially harmful but risk promoting the emergence of drug resistance amongst the parasites that cause the disease, the analysis states. According to the World Malaria Report 2010, it killed 781,000 people in 2009, mainly young children and pregnant women.

The researchers examined anti-malarials collected in eleven African countries between 2002 and 2010, which they believed to be either counterfeit or substandard. Some contained a mixture of wrong active pharmaceutical ingredients, some of which may initially alleviate malaria symptoms but would not cure the disease.

Worse still, these unexpected ingredients could cause potentially serious side effects, particularly if they were to interact with other medications, such as antiretrovirals for HIV. Some of the counterfeits also contained small amounts of artemisinin derivatives, perhaps to try to ensure that the drug would pass simple authenticity tests but taken at such low levels, the drug is unlikely to rid the body of malaria parasites, leading to strains of the parasite resistant to artemisinin.

The researchers also identified pollen found in some of the tablets, indicating that the counterfeits come from eastern Asia. Indeed, in 2001, police in Guangzhou, China, arrested Nigerian and Chinese men for production of fakes of the anti-malarial halofantrine.

No evidence was found from the pollen analysis of counterfeit pharmaceutical production in Africa but production facilities for packaging materials for fake anti-malarials have been seized in Nigeria. Jimmy Whitworth, head of international activities at the Wellcome Trust, said: "This research is very worrying and should act as an early warning. We have already begun to see the emergence of drug-resistant malaria parasites in south east Asia; substandard and counterfeit anti-malarials and the availability of artemisinin monotherapies threaten to lead to the spread of drug resistance in Africa".