"The scale of the Ebola outbreak, and the persistent threat it poses, requires WHO and Guinea, Liberia and Sierra Leone to take the response to a new level, and this will require increased resources, in-country medical expertise, regional preparedness and coordination," Xinhua quoted WHO Director-General Margaret Chan as saying in a statement.
"The countries have identified what they need, and the WHO is reaching out to the international community to drive the response plan forward," she said.
The Ebola Virus Disease Outbreak Response Plan in West Africa identified the need for several hundred more personnel to be deployed in affected countries to supplement over-stretched treatment facilities.
Hundreds of international aid workers, as well as more than 120 WHO staff, are already supporting national and regional response efforts.
The WHO noted the greatest needs were clinical doctors and nurses, epidemiologists, social mobilisation experts and data managers.
According to the WHO, the scale of the ongoing outbreak is unprecedented, with approximately 1,323 confirmed and suspected cases reported, and 729 deaths in Guinea, Liberia and Sierra Leone since March.