Staff at Australian airports are keeping a close eye on the health of people entering the country in light of the killer Ebola epidemic in west Africa.

Incoming flights have on-board announcements asking passengers to advise crew if they feel unwell with fever, chills or sweat, and new information banners will be installed at airports to raise awareness of the symptoms of Ebola.



But the risk of an outbreak in Australia is very low, Health Minister Peter Dutton says.



The World Health Organization has declared the virus's spread a public health emergency of international concern and appealed for global aid to help afflicted countries.



Ebola has claimed at least 932 lives and infected more than 1700 people since breaking out in Guinea earlier this year.



Australians are advised to reconsider their need to travel to Guinea, Sierra Leone and Liberia.



The Abbott government is taking advice from Chief Medical Officer Chris Baggoley, who was on the WHO committee advising the emergency declaration.



Ebola was a serious disease but not highly contagious, Mr Dutton said on Friday.



"Ebola is not influenza, it is not caught through coughing or sneezing," he said.



"It is only caught through contact with the bodily fluids of an infected person or animal."



Border protection agencies are on alert to watch for unwell people at Australian airports, incoming flights have on-board announcements asking passengers to advise crew if they feel unwell with fever, chills or sweat, and new information banners will be installed at airports to raise awareness of the symptoms of Ebola.



There is one Australian official in Liberia as part of a UN operation, AAP understands.

Nigeria declares public health emergency

Meanwhile, Nigeria has confirmed two new cases of Ebola, bringing the total number of infections in Africa's most populous country to nine, including two deaths.

"We have an additional two confirmed cases. So the total now, we have nine confirmed cases (including two deaths). The same two we told you about: the index case and the health worker," Health Minister Onyebuchi Chukwu told journalists.



President Goodluck Jonathan earlier Friday declared a national emergency over the deadly virus.



Nigeria currently has six suspected cases that are under investigation and a total of 139 people have been placed under surveillance, the minister said during a visit to Lagos, Nigeria's commercial capital of more than 20 million people.



"As we talk, we do have six suspected cases currently under investigation...Now altogether, all those we have placed under surveillance stand at 139," he added.



An American-Liberian, who flew into the country from Monrovia, and a Nigerian nurse are the two people who have died of Ebola virus in Lagos in the last two weeks.



The minister said that the government had approved life insurance policy for all those taking care of Ebola virus patients and involved in contact-tracing.



The president earlier called on the population to avoid large gatherings in order to prevent the spread of the virus.



"Religious and political groups, spiritual healing centres, families, associations and other bodies should ... discourage gatherings and activities that may unwittingly promote close contact with infected persons or place others at risk," said a statement issued by the presidency.



Jonathan also approved the immediate release of 1.9 billion naira ($11.6 million, 8.7 million euros) to fund measures against the spread of the virus.



Measures to be taken include the setting up of additional isolation centres, screening at borders and contact-tracing.



In addition, the president warned against any movement of corpses to other parts of the country as well as spreading false information about the virus.



World Health Organisation chief Margaret Chan said in Geneva Friday that the epidemic in west Africa which has killed nearly 1,000 people in Guinea, Liberia, Sierra Leone and Nigeria was the worst of its kind in four decades.