Holidaymakers planning trips to the tropics are being warned to avoid homeopathic remedies that are claimed to prevent malaria after several travellers contracted the potentially fatal disease.

An investigation by the charity Sense about Science found that 10 homeopathic clinics selected at random on the internet offered unproven products which were claimed to prevent malaria and other diseases including typhoid, dengue fever and yellow fever. In all 10 consultations the advice was to use the products rather than conventional anti-malarial drugs.

Tropical medicine specialists condemned the practice. Ron Behrens, director of the Hospital for Tropical Diseases Travel Clinic, said: "We have treated people who thought they were protected by homeopathic medicines and contracted malaria. The messages given by some homeopaths are inaccurate and place lives at risk."

The Faculty of Homeopathy said yesterday it did not recommend homeopathic remedies for malaria prevention. Peter Fisher, clinical director of the Royal London Homeopathic Hospital, said: "There is no published evidence to support the use of homeopathy in the prevention of malaria."