Liberia will receive an untested experimental drug, Zmapp, to treat people infected with Ebola, the Liberian government says.
The move came after a request to the US from Liberian President Ellen Johnson Sirleaf, the government said.
The news came as medical ethics specialists met in Geneva to explore the use of such new treatments.
The World Health Organization, which is hosting the meeting, says some 1,013 have died from Ebola in West Africa.
US government officials said their role had been to put Liberian officials in contact with Zmapp maker Mapp Biopharmaceutical.
The pharmaceutical company said its supply of the drug was exhausted after its supplies were sent to West Africa, AFP news agency reported.
The drug was "provided at no cost in all cases," the company added.
Zmapp has been used in the US on two aid workers who have shown signs of improvement, and a Roman Catholic priest, infected with Ebola in Liberia, who is currently being treated in a hospital in Madrid.
However, the drug has only been tested on monkeys and has not yet been evaluated for safety in humans.
The World Health Organization (WHO) will announce the outcome of its emergency meeting on the role of experimental drugs on Tuesday.
No rock and hard place
Earlier, Ivory Coast announced it had banned all passenger flights from the three countries hit the worst by the spread of Ebola: Guinea, Liberia and Sierra Leone.
It is the second country, after Saudi Arabia, to impose such a ban in a bid to prevent the spread of the deadly virus.
There is no cure for Ebola, which has infected 1848 people since the outbreak was first reported in Guinea in February.
The Liberian government was aware of the risks associated with Zmapp, but the alternative was to allow many more people to die, Information Minister Lewis Brown told the BBC on Monday.
"The alternative for not testing this is death, a certain death," he said,
"This is not even the rock and the hard place for us," he said, referring to the country's health services, which he says are overburdened with patients carrying the disease.
The situation has prompted poorly equipped health workers to abandon work and institutions to close to the public.
Ebola's initial flu-like symptoms can lead to external haemorrhaging from areas like eyes and gums, and internal bleeding which can lead to organ failure. Patients have a better chance of survival if they receive early treatment.
Analysis: Will Ross, BBC News, Lagos
Nigeria has been an example of how controversial a clinical trial can become. In 1996 the US-based pharmaceutical company, Pfizer, carried out a drug trial during a meningitis outbreak in which about 12,000 people died from the disease in the northern state of Kano over six months.
Pfizer gave 100 children an experimental oral antibiotic called Trovan which it said had already been tested on more than 5,000 patients. Pfizer was sued by the government as well as by affected families after 11 children died and dozens were left disabled during the trial - some with brain damage.
The firm argued that meningitis had harmed the children and not the drug. But after lengthy legal battles a multi-million dollar settlement was made with Kano state and in 2011 four families received the first compensation payments.
One key difference between this Ebola outbreak and the 1996 case is that when Pfizer conducted the Trovan trials another meningitis drug was already widely used.
A trial gone wrong can have long-term effects: It is no coincidence that northern Nigeria is one of the few areas in the world where polio remains endemic as the Trovan trial added to suspicion of Western medicine.
Mr Brown said: "We think those who have been infected should be given the chance to have that tested on them if they give their consent to do so."
"We know there may be risks associated with it," the minister added, "but choosing a risk and choosing dying I am sure many would prefer to see that risk happen".
Soldiers have been deployed at checkpoints in two counties worst affected by the outbreak, Lofa and Bomi, to restrict people's movements.
Meanwhile, China has sent medical supplies worth 30m yuan ($4.9m; £2.9m) to Liberia, Sierra Leone and Guinea to help fight against the disease.
Separately, the Chinese ambassador to Sierra Leone said on Monday that eight Chinese medical workers who had been treating Ebola patients had been placed in quarantine for the past two weeks in the capital.
The World Health Organization (WHO) has declared the outbreak in West Africa a global health emergency.
Nigeria, Africa's most populous country, confirmed a 10th case of Ebola on Monday.
Ebola virus disease (EVD)
- Symptoms include high fever, bleeding and central nervous system damage
- Fatality rate can reach 90% - but the current outbreak is about 55%
- Incubation period is two to 21 days
- There is no vaccine or cure
- Supportive care such as rehydrating patients who have diarrhoea and vomiting can help recovery
- Fruit bats are considered to be virus' natural host