GENEVA - Ebola is still spreading quickly in western Sierra Leone and deep in Guinea's forested region, a senior UN official said on Tuesday.

More foreign health workers are needed to combat the epidemic, especially in Sierra Leone where treatment centres are still opening and need expert staff, said David Nabarro, the UN Secretary General's special envoy for Ebola.

"We know the outbreak is still flaming strongly in western Sierra Leone and some parts of the interior of Guinea. We cant rest, we still have to push on," Nabarro told a news briefing in Geneva.