The talks come as countries ravaged by the tropical disease in west Africa are gripped by panic, with drastic measures brought in to contain the epidemic causing transport chaos, price hikes and food shortages, stoking fears people could die of hunger.
There is currently no available cure or vaccine for Ebola, one of the deadliest viruses known to man, and with the death toll fast approaching 1,000, the WHO has declared the latest outbreak a global public health emergency.
But the use of experimental drugs has opened up an intense ethical debate, and medical experts from around the world are set Monday to join WHO-hosted discussions to draft guidelines for using non-authorised medicines in emergencies such as Ebola.
Two Americans and a Spanish priest infected with the virus while working with the sick in Africa are being treated with an untested drug called ZMapp, which has reportedly shown promising results.
But the drug, made by private US company Mapp Pharmaceuticals, is still in an extremely early phase of development and had only been tested previously on monkeys.
It is also in extremely short supply, and the use of the medication on Western aid workers has sparked controversy and demands that it be made available in Africa, where Guinea, Liberia and Sierra Leone are the hardest hit nations.
"Is it ethical to use unregistered medicines to treat people, and if so, what criteria should they meet, and what conditions, and who should be treated?" said WHO assistant director-general Marie-Paule Kieny, who will host Monday's meeting.
"What is the ethical thing to do?"
- I.Coast bans flights -
While impoverished Guinea, Liberia and Sierra Leone account for the bulk of the cases, the latest outbreak has spread further afield, with Nigeria, Africa's most populous country, counting two deaths.
Numerous countries have imposed a raft of emergency measures, including flight bans or screening of passengers.
In the latest such move, the Ivory Coast announced Monday it was banning all flights from the three hardest-hit nations.
Ebola causes fever and, in the worst cases, unstoppable bleeding, and can be fatal in up to 90 percent of cases, according to the WHO.
The virus spreads by close contact with an infected person through bodily fluids such as sweat, blood and tissue.
The latest outbreak -- which the WHO says is by far the worst since the virus was discovered four decades ago -- has killed around 55-60 percent of those infected.
The WHO said Saturday that clinical trials of vaccines against Ebola should begin soon and will likely be ready for widespread use by early next year.
"I think it's realistic," Kieny told AFP.
ZMapp appears to have been efficient in two repatriated American aid workers and which is now being administered to an infected Catholic priest repatriated to Spain.
But there are only about a handful of available treatments, and it remains unclear how quickly production could be ramped up.
As WHO engages with pharmaceutical companies and governments to try to speed up the development process of vaccines and drugs, it is faced with a range of pressing ethical questions.
Should anyone infected with the virus be given experimental treatments? And what about those who have been exposed, or who could easily become exposed due to their work, such as health care workers?
Monday's meeting, whose conclusions are due for release on Tuesday, will also look at how far testing must have progressed before an experimental drug can be provided, said Kieny.
"Is there a set of characteristics that these unregistered medicines should meet in terms of having demonstrated efficacy in terms of safety data, and in how many humans?"
Kieny said the session would only address the principles and provide guidance to the WHO on how to proceed, but that the UN agency planned a longer meeting later to look further into the issue.