A drug used to treat UK patients with malaria has failed for the first time, scientists have found.

Four patients who presented with signs of the tropical disease, which is spread by mosquitoes, had to seek alternative treatment after the drug commonly used to tackle malaria did not work.

Research by the London School of Hygiene and Tropical Medicine (LSHTM) said the treatment failure was due to strains of the disease showing reduced susceptibility and a "potential first sign of drug resistance" to artemether-lumefantrine (AL).