West Africa's raging epidemic of the Ebola virus has been declared an international public health emergency by the World Health Organisation (WHO).

Holding an emergency meeting, the Geneva-based UN health agency said the possible consequences of further spread are "particularly serious" given the virulence of the virus.

WHO chief Margaret Chan has described the outbreak as an extraordinary event and a risk to other countries, and said a coordinated international response was required.

"I am declaring the current outbreak of Ebola virus ... a public health emergency of international concern," she said.

"The committee's decision was unanimous. It's advice to me acknowledges the serious and unusual nature of the outbreak and the potential for further international spread."

It is expected that WHO will be meet again next week to consider the ethics of using experimental medicines to deal with the outbreak.

The death count has now climbed to almost 1,000 people, in Guinea, Sierra Leone and Liberia.

WHO's emergency declaration comes as the United States orders the families of embassy staff in Liberia to return home, as West Africa struggles to cope with the world's biggest ever outbreak of Ebola.

The State Department has also warned US citizens not to travel to Liberia, repeating an earlier instruction from American health authorities.

Security forces in Sierra Leone and Liberia have set up blockades to stop people from the worst-affected areas travelling, and Liberia has declared a state of emergency.

Risk to Australia 'very low': Peter Dutton

Despite WHO's announcement, Health Minister Peter Dutton says the risk to Australia remains "very low".

"The WHO declaration recognises the seriousness of the Ebola outbreak in West Africa. Its recommendations are aimed at the affected, transmitting countries and also provide guidance for nearby countries to help manage any further spread," he said.

"The broader recommendations for the rest of the world are consistent with current Australian border protection measures, which are already efficient."

Mr Dutton says he is receiving advice from Australia's chief medical officer, Professor Chris Baggoley, who was a member of the WHO committee that issued today's public health emergency warning.

"In overseeing Australia's national response, Professor Baggoley advises that while Ebola is a very serious disease, it is not highly contagious," he said.

Mr Dutton says airline crews are working with Australian border protection agencies to identify any unwell travellers who may pose an Ebola risk.

"Incoming flights to Australia have onboard announcements, asking passengers who are feeling well with fever, chills or sweats to alert a crew member ... [who] would alert border protection and biosecurity staff for health follow-up," he said.

Outbreak causing panic as residents 'afraid' of victims

The outbreak is causing panic on the streets of those countries affected.

In Guinea, - which has seen 360 perish so far - it has created fear among locals when they come across those who are unwell.

One Guinea resident said: "We came here this morning and we saw this man who collapsed on the street. I don't know whether he was suffering from Ebola or not. Let them come and take him from here because we are afraid."

In Madrid, a priest who contracted Ebola in Liberia was flown back to the Spanish capital in a specially-equipped Airbus to a hospital which had been cleared for his arrival.

A spokesman for the city's health department, Antonio Alemany, says the priest and a nun, who are both being isolated as a precautionary measure, are doing well.

"The state of the two patients, Miguel and the nun, is stable," Mr Alemany said. "They don't have fever and more importantly Father Miguel has no haemorrhaging symptoms."

Wider acceptance threat of Ebola is real: Doctor

Despite the rising number of cases, a British doctor working in a hospital in Sierra Leone's capital Freetown, says the situation now feels more under control.

Dr Oliver Johnson, from King's College London, says there was a lot of suspicion at the beginning of the outbreak.

"And so what we saw is a lot of people [who] believed that Ebola wasn't real. And sometimes fear of going to hospitals and fear of health workers," Dr Johnson said.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Listen Duration: 3 minutes 21 seconds 3 m 21 s Barbara Miller speaks to British doctor in Sierra Leone Download 6.1 MB

"And what that meant is that people were keeping sick people at home. Family members were becoming sick.

"What we're now seeing is a much wider acceptance amongst the public that Ebola is real. We're hoping that we're going to see more and more people come to hospital when they get sick.

"And we're seeing disease surveillance officers, community health volunteers picking up on cases early and preventing sick people from travelling between different parts of the country."

Dr Johnson agrees the outbreak is creating panic among locals, frightened any symptoms of flu may be a sign of Ebola.

"Anyone who coughs or sneezes, there's a funny look," Dr Johnson said.

"People aren't shaking hands in Freetown any more. There are buckets of chlorine at every restaurant, every office to wash your hands in.

"A lot of people wander the city wearing medical gloves. So there's a high awareness. There is a degree of caution."

He says there is also concern among his staff.

"All of us are aware that health workers have died," he said.

"Doctors and nurses in Sierra Leone have died. And there's no doubt that it's caused anxiety.

"I say in the last few days, though, there's been an acceptance of the risk and a recognition that Ebola's going to be around for a little while.

"And I think people are beginning to calm down right now and feel that the risk is something they need to accept, just [like] the risks that exist for health workers in hospitals."

ABC/Reuters