The World Health Organization authorised the use of experimental drugs in the fight against Ebola on Tuesday as the death toll topped 1,000 and a Spanish priest became the first European to succumb to the latest outbreak of the virus.
The declaration by the UN's health agency came after a US company that makes an experimental serum said it had sent all its available supplies to hard-hit west Africa.
"In the particular circumstances of this outbreak, and provided certain conditions are met... it is ethical to offer unproven interventions with as yet unknown efficacy and adverse effects," the WHO said in a statement following a teleconference between medical experts.
The current outbreak, described as the worst since Ebola was first discovered four decades ago, has now killed 1,013 people since early this year, the WHO said.
Cases have so far been limited to Guinea, Liberia, Sierra Leone and Nigeria, all in west Africa where ill-equipped and fragile health systems are struggling to cope.
Elderly Spanish priest Miguel Pajares, who became infected while helping patients in Liberia died in a Madrid hospital on Tuesday, five days after being evacuated.
Monrovia said it had requested samples of an experimental drug, ZMapp, that has shown some positive effects on two US aid workers but failed to save the Spanish priest.
Supplies would be brought in by a representative of the US government later this week, the Liberian government said.
There is currently no available cure or vaccine for Ebola, which the WHO has declared a global public health emergency, and the use of experimental drugs has stoked an ethical debate.