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.

Organisations combating the outbreak needed to scale-up efforts “three-to-four fold”, the WHO said.

It highlighted Liberia’s Montserrado county, where 1,000 beds were needed for infected Ebola patients but only 240 were available, leading to people being turned away from treatment centres.

Transmission of the virus in Liberia was “already intense”, and taxis being used to transport infected patients appeared to be “a hot source of potential virus transmission”, the WHO said.

“As soon as a new Ebola treatment facility is opened, it immediately fills to overflowing with patients, pointing to a large but previously invisible caseload,” it added.

“When patients are turned away… they have no choice but to return to their communities and homes, where they inevitably infect others.”