The tally of Ebola-related deaths has passed the grim milestone of 10,000, mostly in West Africa, the World Health Organisation (WHO) said.

The UN health agency said on Thursday that Guinea, Liberia and Sierra Leone alone had reported 10,004 confirmed, probable and suspected deaths from the virus since the beginning of the biggest-ever Ebola outbreak in March 2014.

There have also been eight deaths in Nigeria, six in Mali and one in the United States.

A massive international effort to stamp out the deadly disease has slowed the rate of infections, especially in Liberia. But the virus appears stubbornly entrenched in parts of Guinea and Sierra Leone.

WHO's statement came after authorities in Sierra Leone reported a worrying spike in infections over the past week in four districts.

Alfred Palo Conteh, the head of the National Ebola Response Centre, said that new Ebola hotspots have emerged in recent days in Cabala Town and Magazine Cut in the east of the capital, Freetown, where a number of confirmed cases have been recorded. The other hotspot is in the west of Freetown.

Palo Conteh added that the increase in infections of the contagious disease was caused by a lack of public caution in "densely populated" areas.

Source: Agencies