MONROVIA, Liberia -- Liberian officials confirmed a second Ebola case Wednesday in the same town where the disease was detected days earlier on the corpse of a teenager, seven weeks after the country was declared Ebola-free.

The infected person was moved to Monrovia, said Deputy Health Minister Tolbert Nyenswah.

More than 100 Ebola centre workers stormed the Ministry of Health in eastern Monrovia on Wednesday demanding hazard pay that they said they haven't received since the country was declared Ebola-free May 9 by the World Health Organization.

Health Minister Bernice Dahn said Liberia has paid hazard benefits to "99 per cent" of people who worked in the Ebola treatment units in addition to their regular salaries. She said if there are people who feel they have not been paid, "they should come forward" and make their case with the ministry.

Also Wednesday, workers exhumed the body of the 17-year-old male student whose infection, detected after his death, sparked fears of the return of Ebola to Liberia. The country was the hardest hit in the region, with 4,800 deaths, before it contained transmission.

New tests will help determine the mode of transmission to the teenager, said an official speaking on condition of anonymity because he was not permitted to speak to media.

The World Health Organization said the 17-year-old first became ill June 21 and went to a local health facility where he was treated for malaria and discharged.

Those tracking the case have identified 102 contacts, although that number is expected to increase as investigations continue, WHO said.

Experts warn that Ebola remains a threat to West Africa until it is eradicated from Guinea and Sierra Leone where it stubbornly hangs on.

The West African outbreak of Ebola is the worst ever recorded, killing more than 11,200 people.