The World Health Organisation (WHO) has promised to undertake and publish a full review of its handling of the Ebola crisis after a leaked document appeared to show the UN agency had failed to do enough to contain the epidemic.

The WHO said in a statement on Saturday that it would not comment on an internal draft document obtained and released by the Associated Press news agency, in which the organisation blamed incompetent staff, bureaucracy and a lack of reliable information for its allegedly slow and weak response to the outbreak that has reportedly killed more than 4,500 people since May.

"We cannot divert our limited resources from the urgent response to do a detailed analysis of the past response. That review will come, but only after this outbreak is over," WHO said.

The document - a timeline of the outbreak - found that WHO, an arm of the United Nations, missed chances to prevent Ebola from spreading soon after it was first diagnosed in Liberia, Sierra Leone and Guinea last spring,

WHO Director General Margaret Chan has defended her handling of the epidemic.

'Politically motivated appointments'

But the leaked document said experts should have realised that traditional containment methods would not work in a region with porous borders and weak health systems.

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"Nearly everyone involved in the outbreak response failed to see some fairly plain writing on the wall," the document said.

The agency also said that its own bureaucracy was part of the problem, according to the report. It pointed out that the heads of its country offices in Africa are "politically motivated appointments".

Peter Piot, the co-discoverer of the Ebola virus, agreed that WHO acted far too slowly.

"It's the regional office in Africa that's the frontline," said Piot, interviewed at his office in London. "And they didn't do anything. That office is really not competent."

The African office declared Ebola to be "pretty much contained" in Senegal and Nigeria on September 22, a claim not backed up by Chan's office, which only declared Senegal to be Ebola-free on Friday and has yet to say the same about Nigeria.

The leaked document also said one of Chan's senior officials, Bruce Aylward, had warned her by email that some of the WHO's partners felt it was "compromising rather than aiding" the Ebola response and that "none of the news about WHO's performance is good."

Ebola has killed at least 4,546 people in Liberia, Sierra Leone and Guinea, the WHO said on Friday. However, with at least half the cases going unreported and a 70 percent fatality rate, by WHO estimates, the true toll is probably more than 12,000.

Source: Agencies