CRITICS have hit out after the US military isolated soldiers returning from an Ebola response mission in West Africa and Australia imposed a visa ban on the affected countries, saying the policies would have little benefit but could feed global panic.

Ebola has killed nearly 5,000 people since March, mostly in West Africa, but nine cases in the US prompted states such as New York and New Jersey to ignore federal advice and quarantine all health workers returning from the region.

The United Nations criticised the US states' mandatory quarantine imposed on those returning from Liberia, Guinea and Sierra Leone.

"Returning health workers are exceptional people who are giving of themselves for humanity," said Secretary-General Ban Ki-moon's spokesman Stephane Dujarric. "They should not be subjected to restrictions that are not based on science."

The World Health Organization said it feared the quarantine measures could put people off volunteering to go to Africa.

"We desperately need inter-national health workers. They are the key to this response," said WHO spokesman Tarik Jasarevic.

Australia is the first rich country to impose a visa ban on the three countries hit by Ebola, prompting anger across Africa.

"Western countries are creating mass panic which is unhelpful in containing a contagious disease like Ebola," said Ugandan govern-ment spokesman Ofwono Opondo.

"If they create mass panic ... this fear will eventually spread beyond ordinary people to health workers or people who transport the sick and then what will happen? Entire populations will be wiped out."

Eighty-two people who had contact with a toddler who died of Ebola in Mali last week are being monitored, the WHO said, but no new cases have been reported there.

Mali became the sixth West African country to report a case of the disease. Senegal and Nigeria both stopped the virus by tracking down people who had had contact with the person who brought it into their country and monitoring them for symptoms.

Nato said it was talking with the UN about what help the military alliance might be able to provide.

Nato Secretary-General Jens Stoltenberg said: "The question is not whether Nato allies are contributing in fighting Ebola. The question is whether this is best organised through a Nato struc-ture, and that's too early to say."

American soldiers returning from West Africa are being isolated, even if they show no symptoms and are not believed to have been exposed to the virus. The Army said Chief of Staff General Raymond Odierno ordered the 21-day monitoring period "to ensure soldiers, family members and their communities are confident we are taking all steps necessary to protect their health."

The Army isolated about a dozen soldiers on their return to their home base in Vicenza, Italy, at the weekend. That included Major General Darryl Williams, the commander of US Army Africa, who oversaw the military's initial response to the Ebola outbreak.

"We are billeted in a separate area. There's no contact with the general population or with family. No one will be walking around Vicenza," Williams said. The US military has stressed its personnel are not interacting with Ebola patients but building treatment units to help health authorities battle the epidemic.

Up to 4,000 US troops may be deployed on the mission.