The charity Medecins sans Frontieres (MSF) says Liberia's medical services have been completely overwhelmed by the Ebola outbreak.
The MSF co-ordinator in Liberia said official figures were "under-representing the reality", and that the health system was "falling apart".
Nearly 1,000 people have died and 1,800 have become infected in West Africa.
On Saturday Liberian police broke up a protest against the government's response.
The Ebola outbreak – the worst ever – is centred on Liberia, Sierra Leone and Guinea, but has spread to other countries in recent months.
The World Health Organization (WHO) said on Friday that the virus was a global health emergency.
The MSF co-ordinator for Liberia, Lindis Hurum, said "Our capacity is stretched beyond anything that we ever done before in regards to ebola response."
She said five of the biggest hospitals in the capital Monrovia had closed for more than a week.
"Some of them have now started to re-open but there are other hospitals in other counties that are just abandoned by the staff. We are definitely seeing the whole health care system that is falling apart," Lindis Hurum lamented.
On Saturday demonstrators in Liberia blocked a highway, saying authorities had not been collecting the bodies of some victims.
The army was then deployed to restrict movement, particularly from the worst-affected provinces to the capital.
In Guinea, the health minister on Saturday said the borders with Liberia and Sierra Leone had been closed to prevent infected people crossing into the country.
The Ebola virus was first discovered in the Democratic Republic of Congo in 1976. It is transmitted between humans through bodily fluids.
Animals such as fruit bats carry the virus, which can be transmitted to humans through contact with blood or consumption of bush meat.