The World Health Organization on Friday declared the killer Ebola epidemic ravaging parts of west Africa an international health emergency and appealed for global aid to help afflicted countries.

The decision after a two-day emergency session behind closed doors in Geneva means global travel restrictions may be put in place to halt its spread as the overall death toll nears 1,000.

The WHO move comes as US health authorities admitted on Thursday that Ebola's spread beyond west Africa was "inevitable", and after medical charity Doctors Without Borders (MSF) warned that the deadly virus was now "out of control" with more than 60 outbreak hotspots.

WHO director-general Dr Margaret Chan appealed for greater help for the countries worst hit by the "most complex outbreak in the four decades of this disease", echoing an earlier claim by MSF that the "epidemic is unprecedented in terms of geographical distribution, people infected and deaths".

"I am declaring the outbreak a public health emergency of international concern," Chan said, stressing the "serious and unusual nature of the outbreak".

Even as a possible new case was reported in the east African country of Uganda, she said only a small part of the continent had been affected. "This alerts the world to the need for high vigilance," she said.

Ebola has claimed at least 932 lives and infected more than 1,700 people since breaking out in Guinea earlier this year, according to the WHO.

States of emergency were in effect in Liberia, Guinea and Sierra Leone.

Source: AFP