Ebola Nurse Amber
Ebola Nurse Amber

The U.N. secretary-general warned Monday against "unnecessarily extra restrictions” on health workers returning from treating Ebola patients.

Speaking at a U.N. conference in Vienna, Ban Ki-Moon described a quarantine for health workers as "not based on science and medical evidence," calling it a discriminatory measure against them.

"They are extraordinary people who are...risking their own lives," Ban said. "The best way to stop this virus is to stop the virus at its source rather than limiting or restricting the movement of people or trade."

Canada and Australia have banned entry of citizens from Liberia, Sierra Leone and Guinea, where the disease is widespread. Some U.S. politicians have called for a similar ban by the United States, a measure opposed by the federal government.

In a related development, a nurse in the U.S. state of Maine who had treated Ebola patients in Sierra Leone obtained a court order not to be quarantined.

And a doctor in Sierra Leone died of Ebola, making him the fifth local doctor to lose his life due to hemorrhagic fever associated with the disease.

Almost 5,000 people have succumbed to Ebola, according to the World Health Organization. WHO has recorded more than 13,000 cases, mostly in West Africa, but has said the real number could be even higher.