The virus has claimed 1,013 lives and has infected a further 1,848 people globally since the latest outbreak in March, data from the WHO has shown. The West African countries of Guinea, Liberia and Sierra Leone have been most affected by the spread of Ebola.

Meanwhile, US President Barack Obama and the US Food and Drug Administration (FDA) have approved a request by Liberia for an experimental drug called ZMapp, made by Californian firm Mapp Biopharmaceutical, to be shipped the West African country.

Liberia's Information Minister Lewis Brown has told the Reuters news agency that Liberia will receive just enough of the drug to treat two infected doctors.

Brown said Liberia's Health Ministry had contacted Mapp Biopharmaceutical, and asked the FDA to quickly approve its export.

The doctors had consented in writing to the treatment, the minister told Reuters.

So far, two Americans and a Spaniard have received the drug. The two American missionary workers who fell ill with Ebola while working in Liberia's capital, Monrovia, last month, were given the treatment after returning to the US. A Spanish priest who was sickened with the virus has also been given a dose and returned to Spain.

Ebola is a type of hemorrhagic fever that is often fatal. It is highly contagious, but not airborne. The infection is transmitted by direct contact with the blood, body fluids and tissues of infected animals or people.

ng/kms (epd, Reuters, AFP)