Ebola is spreading exponentially in Liberia, with thousands of new cases expected in the next three weeks, the World Health Organization (WHO) says.
Conventional methods to control the outbreak were "not having an adequate impact", the UN's health agency added.
At least 2,100 people infected with Ebola have died so far in the West African states of Guinea, Liberia, Sierra Leone and Nigeria this year.
The WHO says 79 health workers have been killed by the virus, according to BBC.
Organizations combating the outbreak needed to scale-up efforts "three-to-four fold", the WHO said.
Three countries - Guinea, Sierra Leone and Liberia - are at the heart of the Ebola outbreak, but Liberia is suffering the most by far. Why this is the case is not completely understood. Finding the answer will be a critical part of tackling the outbreak.