Authorities in Liberia have opened a new centre to treat Ebola patients in the capital after the existing one became overwhelmed with patients.

The first centre in Monrovia was only meant to treat 25 people but had about 80 patients as of Friday, said Assistant Health Minister Tolbert Nyenswah. The new centre will have 120 beds but may eventually be tripled in size because of the ongoing crisis.

Isolating Ebola patients is critical to slowing the spread of the disease, as sick people can transmit it through their bodily fluids such as blood, sweat or urine. There is no licensed treatment or vaccine for the disease, which has killed at least half of its victims this year.

Even as authorities rush to put patients in isolation, the UN health agency has warned that the Ebola outbreak in West Africa may last another six months. At least 1,145 people have died across Liberia, Sierra Leone, Guinea and Nigeria, and that may "vastly underestimate the magnitude of the outbreak," the World Health Organisation says.

New figures released yesterday showed that Liberia now has recorded more deaths - 413 - than any of the other affected countries.

Health workers treating Ebola patients on the front lines of the crisis have borne the brunt of the fatalities. Sierra Leone's president, Ernest Bai Koroma, said that his country has lost two top doctors and 32 nurses.

"We need specialised clinicians and expertise and that is why we are appealing to the international community for an enhanced response to our fight against the Ebola disease," he said.