The World Health Organisation says it is ethical to offer “unproven interventions with as yet unknown efficacy and adverse effects, as potential treatment or prevention” to the Ebola outbreak in west Africa.

The advice comes after the WHO consulted with a team of experts, including Wellcome Trust director Jeremy Farrar,  who concluded that the high case-fatality rate means that using unlicensed treatment is an option. The agency said that “ethical criteria must guide the provision of such interventions”, including “transparency about all aspects of care, informed consent, freedom of choice, confidentiality, respect for the person, preservation of dignity and involvement of the community”.

The WHO advisors added that if and when unapproved drugs are used, “there is a moral obligation to collect and share all data generated, including from treatments provided for compassionate use”. Over 1,000 people have now died from Ebola.

The announcement came as Liberia revealed that it would start using Zmapp, an unapproved cocktail of three antibodies against Ebola being developed by small US firm Mapp Biopharmaceutical. To date, it has only been given to two US aid workers who contracted Ebola in Liberia and are showing signs of recovery and also reportedly to a 75-year-old Spanish missionary who died earlier today in Madrid after being evacuated from Liberia.

However, Mapp, which employs nine staff and has been financed solely by government grants and contracts, has issued a statement saying that its supply has been exhausted after the company provided doses to an unnamed West African nation.

UPDATE: In response to the crisis, Canada says it will donate 800-1,000 doses of an experimental Ebola vaccine it has developed, but which has only been tested on animals, for use in West Africa.

The country’s Public Health Agency noted that it will also keep a small supply of the experimental vaccine “in the unlikely event it is needed for compassionate use in Canada”. The WHO will help to facilitate distribution of the vaccine.