Signs that Ebola "may be levelling off" in Sierra Leone - WHO

* Sierra Leone still records 248 new cases in past week

* More than 8,000 killed worldwide in epidemic to date

* WHO to host meeting on experimental vaccines on Thursday (adds details, byline)

By Stephanie Nebehay

GENEVA, Jan 7 (Reuters) - Sierra Leone, the country worst affected by Ebola, reported nearly 250 new confirmed cases in the past week but the spread of the virus there may be slowing, the World Health Organization (WHO) said on Wednesday.

The epidemic has taken 8,235 lives out of 20,747 known cases worldwide over the past year, it said.

The WHO's weekly report was based on figures reported by authorities in nine countries. Guinea, Liberia and Sierra Leone account for the majority of infections and fatalities.

"There are signs that case incidence may have levelled off in Sierra Leone, although with 248 new confirmed cases reported in the week to 4 January 2015, it remains by far the worst-affected country at present," the WHO said.

Cases are still under-reported and unevenly spread in West Africa. The virus is spreading most rapidly in western Sierra Leone, where the capital Freetown reported 93 of the new confirmed cases, the WHO said.

"An increasing emphasis will be put on the rapid deployment of smaller treatment facilities to ensure that capacity is matched with demand in each area," the WHO said.

In Guinea, whose capital Conakry remains the worst-affected district, the western prefecture of Fria reported its first Ebola cases.

In Liberia, cases dropped from a peak of more than 300 new confirmed cases per week in August and September to eight new confirmed cases and 40 probable cases in the five days to Jan. 2, it said.

Overall, 838 health workers have been infected, killing 495 of them, the WHO said.

On Thursday, the WHO will host a meeting of representatives from major drug makers, health authorities in affected countries and national regulatory agencies to assess clinical trials of experimental vaccines against Ebola. GlaxoSmithKline (Other OTC: GLAXF - news) , Merck (Other OTC: MKGAF - news) and NewLink Genetics (Munich: 4NX.MU - news) , and Johnson & Johnson (NYSE: JNJ - news) - are currently testing experimental vaccines.

(Reporting by Stephanie Nebehay, Editing by Angus MacSwan)