A doctor in Mali died of Ebola on Thursday after treating an imam who succumbed to the disease, taking the total toll in the west African country up to seven, health authorities said.

The World Health Organization said the virus was "almost certainly re-introduced into Mali by a 70-year-old Grand Imam from Guinea, who was admitted to Bamako's Pasteur clinic on 25 October and died on 27 October."

The doctor had been undergoing treatment for Ebola for nearly two weeks, according to the ministry.

"The infected patient who was being treated and who was improving yesterday died today," a spokesman for the health ministry told AFP.

A total of five infections, all of which have proved fatal, were now linked to the imam.

As well as the doctor they include a male nurse who cared for the imam at the Pasteur clinic, and a 51-year-old friend who came to visit the imam.

A two-year-old girl also died from the disease last month in an unconnected case in the western town of Kayes.

The said a total of 303 people were under surveillance and had their temperatures taken twice a day.

The Malian government had on Wednesday cited a figure of 413 people being monitored.

The WHO said Wednesday 5,420 people have died from Ebola in the current outbreak, mostly in Liberia, Sierra Leone and Guinea.

Ebola, one of the deadliest viruses known to man, is spread only through direct contact with the bodily fluids of an infected person showing symptoms such as fever or vomiting.

People caring for the sick or handling the bodies of people infected Ebola are therefore especially exposed.