WASHINGTON (AFP) - A doctor from Sierra Leone who was being treated at a US hospital for Ebola has died, the Nebraska Medical Center said Monday.

"We are extremely sorry to announce that the third patient we've cared for with the Ebola virus, Dr. Martin Salia, has passed away as a result of the advanced symptoms of the disease," said the hospital in a statement.

The hospital said it would "tentatively" schedule a press conference was announced at 11:00 (1.00 am Tues Singapore time) to brief reporters on the details.

Dr Salia, a native of Sierra Leone and a US resident, was infected with the deadly hemorrhagic fever while treating patients in his home country.

He was flown to Nebraska for treatment on Saturday.

The hospital said late Sunday that Salia was in "extremely critical" condition and that doctors were doing everything they could to save him.

Dr Salia was the 10th person with Ebola to be treated in the United States, and the second to have died from the infection.

In October, a Liberian man, Thomas Eric Duncan, died at a Texas hospital of the virus which has killed thousands of people in West Africa in history's largest ever outbreak.

The World Health Organization said Friday that 5,177 people are known to have died of Ebola across eight countries, out of a total 14,413 cases of infection, since December 2013.

"It is with an extremely heavy heart that we share this news," said Phil Smith, medical director of the Biocontainment Unit at Nebraska Medical Center. "Dr. Salia was extremely critical when he arrived here, and unfortunately, despite our best efforts, we weren't able to save him."

When Dr Salia first began to show symptoms of Ebola in Sierra Leone, a test for the virus came back negative, according to the Washington Post. A second test, on November 10, was positive.

Dr Salia and his wife lived in New Carrollton, Maryland, a suburb of the US capital Washington. They have two children, age 12 and 20. "We're very grateful for the efforts of the team led by Dr. Smith," said his wife, Isatu, in a statement.

"In the short time we spent here, it was apparent how caring and compassionate everyone was. We are so appreciative of the opportunity for my husband to be treated here and believe he was in the best place possible."