Liberian President Ellen Johnson Sirleaf said on Tuesday she expects the Ebola crisis gripping her country to worsen in the coming weeks as health workers struggle with inadequate supplies, a lack of outside support and a population in fear.

"It remains a very grave situation," she told an audience at Harvard University in Cambridge, Massachusetts, via Skype from Liberia's capital Monrovia. "It is taking a long time to respond effectively(...) We expect it to accelerate for at least another two or three weeks, before we can look forward to a decline."

The death toll from the worst Ebola outbreak in history has hit at least 2,296 across West Africa, with more than half of those cases in the impoverished and war-damaged state of Liberia, the World Health Organization said on Tuesday.

Liberia's national defense minister told the United Nations Security Council earlier on Tuesday that Ebola posed a threat to the country's national existence and was "spreading like wild fire and devouring everything in its path."

Sirleaf said Liberia's response to the disease was hobbled by a lack of treatment and testing centers, a dearth of health care workers, and persistent fear and ignorance of the disease among the country's population.

"We have tried to cope with limited support internationally, and with a population that did not give the caution that was required… and this facilitated the spread of the disease," she said, adding some Liberians were not reporting cases and were ignoring suggested precautions to avoid infection.

She said that since the Ebola epidemic began to accelerate in recent weeks she has seen more support from international partners such as the United States, the European Union and African nations, but "it is still far behind the need."

She said the Ebola crisis had also triggered a broader health resources crunch that was proving lethal for people with other diseases. "We need support rebuilding those health systems so that people who do not have Ebola will not lose their lives.”

She added the epidemic was setting back the country's progress rebuilding from successive civil wars between 1989 and 2003, as mining and agricultural companies slow or shutter operations, and cross border trade vanishes.

"This will cost us quite a bit and it will take us some time to get back to the level of progress that we had," she said.

Ebola is a hemorrhagic fever spread through body fluids such as the blood, sweat or vomit of those who are infected with the disease. Health care workers are among the most vulnerable to the disease.

In Guinea and Sierra Leone, the other two countries at the centre of the outbreak, only 39 percent of cases and around 29 percent of deaths have occurred in the past three weeks, according to the WHO, suggesting they are doing better at tackling the outbreak.

Sirleaf said she hoped the crisis would rekindle efforts to find a cure for Ebola, which was first identified in Africa in 1976.