THE World Health Organisation today declared the ebola outbreak in West Africa to be an international public health emergency.

WHO chief Dr Margaret Chan said the announcement was "a clear call for international solidarity."

"Countries affected to date simply do not have the capacity to manage an outbreak of this size and complexity on their own," Dr Chan said in Geneva. "I urge the international community to provide support on the most urgent basis possible."

The present outbreak of ebola is the largest and longest ever recorded.

The disease has a death rate of about 50 per cent and has so far killed at least 932 people.

The outbreak began in Guinea in March and has since spread to Sierra Leone and Liberia with a suspected cluster in Nigeria.

There is no licensed treatment or vaccine.

However, the WHO declaration was dismissed as too little, too late by some health experts.

"Statements won't save lives," said Doctors Without Borders director of operations Dr Bart Janssens.

"For weeks, we have been repeating that a massive medical, epidemiological and public health response is desperately needed…. Lives are being lost because the response is too slow” he warned.

"I don't know what the advantage is of declaring an international emergency," added Dr David Heymann, who directed the WHO response to the Sars outbreak and is now a professor at the London School of Hygiene and Tropical Medicine.

"This could bring in more foreign aid, but we don't know that yet," he said.