In a rare case, two workers at Frankfurt airport have died from malaria after being infected by a mosquito that arrived on a flight. Health officials are monitoring the situation closely.

Two workers at Germany's Frankfurt airport who caught malaria from a mosquito thought to have arrived on a plane have died, the city's health authority said.

Airport officials had earlier said one employee had perished, with six workers infected.

The Robert Koch Institute (RKI) said an imported Anopheles mosquito carried over by an aircraft was the likely cause.

The other four infected employees were being treated in hospital, said an airport spokesman.