Two doctors died of Ebola in Sierra Leone on Friday, a government and a hospital source said, bringing to 10 the number of doctors killed in the country by the virus.

The worst Ebola outbreak on record has torn through some of West Africa's weakest health systems, killing nearly 350 medical personnel, including 106 in Sierra Leone.

The latest figures from the World Health Organization showed Ebola has killed nearly 6,200 people, mainly in Liberia, Sierra Leone and Guinea, since it was confirmed in the region earlier this year.