The United Nations has set a goal of stopping the spread of the deadly Ebola outbreak within the coming six to nine months.

After meeting with top health officials, UN chief Ban Ki-moon said the "next few weeks will be crucial" to step up international efforts to combat the world's worst-ever Ebola outbreak.

Meanwhile, the World Health Organization is due to issue advice on potential treatments for Ebola later today.

It comes after a meeting of medical experts in Geneva to examine the potential effectiveness of a number of experimental treatments and possible vaccines.

The current outbreak of Ebola in West Africa has been the most deadly yet having killed almost 2,000 people.

Meanwhile, a third US health missionary infected with the virus in Liberia left the West African country's capital last night in a plane headed for the Nebraska Medical Centre in Omaha, the Christian organisation SIM USA said.

Liberian Information Minister Lewis Brown confirmed that the plane carrying the worker, Dr Rick Sacra, 51, a Boston physician, was identical to the Gulfstream jet that ferried Nancy Writebol and Dr Kent Brantly, who contracted the disease in July while working at SIM USA'S health centre in Liberia, back to the US.

Timeline of the Ebola outbreak

The Nebraska facility is similar to the one at Atlanta’s Emory University where Ms Writebol and Dr Brantly were treated.