Sierra Leone has announced that it will impose a four-day, countrywide "lockdown" in an escalation of efforts to halt the spread of Ebola across the West African nation, Al Jazeera reported.

Citizens will not be allowed to leave their homes between September 18 and September 21 in a bid to prevent the disease from spreading further and to allow health workers to identify cases in the early stages of the illness, a presidential advisor on the country's Ebola task force said on Friday.

Ibrahim Ben Kargbo told the Reuters news agency that the aggressive approach was necessary "to deal with the spread of Ebola once and for all".

Sierra Leone has recorded 491 of the total of 2,097 deaths blamed on Ebola in West Africa since March, UN figures showed.

The move comes as international health experts met in Geneva, Switzerland, for the second day of urgent talks to fast-track the use of experimental Ebola drugs.

With no fully tested treatments for Ebola available, the World Health Organisation has endorsed potential cures, such as Zmapp, to be rushed out.

The drug has been given to about 10 health workers who contracted the virus, including Americans and Europeans, three of whom recovered.

The two-day closed-door meeting of about 200 health experts in Geneva is discussing eight potential therapies, as well as two experimental vaccines.