Hope remains that it will be possible to bring under control an Ebola outbreak that is currently outpacing containment efforts and is now the second most lethal on record, a World Health Organization (WHO) official said on Tuesday.

The global health agency said earlier this month that reversing Ebola's spread would be possible within a three-month period, but since then there have been signs that it has worsened, expanding to a sixth province.

"About the next plan for the three months, yes, if you have the necessary resources, I think it will be possible to do that," Thierno Balde, WHO incident manager, told reporters in Geneva by video link from Bunia, in the Democratic Republic of Congo.

Resources are currently lagging requirements, and the WHO has raised about 60% of the $115-million it is seeking for the Ebola response.

Still, containment efforts are ramping up and an extra 400 beds have been added in the past two weeks, Balde said. 

The WHO Emergency Committee meets on Tuesday to discuss the outbreak, which was deemed a global emergency by the UN agency on May 17.