An unidentified illness has claimed the lives of 13 people in the northwestern Democratic Republic of Congo.

According to the country's health minister Dr Felix Kabange Numbi, "All 13 people who have died suffered from a fever, diarrhoea, vomiting and, in a terminal stage, of vomiting a black matter."

It's understood that around 80 people who have come into contact with the deceased are being monitored at their homes, he said in an AFP report.

One suggestion is that the deadly disease is a haemorrhagic fever. But a World Health Organisation (WHO) official and the medical charity Doctors Without Borders (MSF) said it was too early to know whether this caused the deaths.

"Many died presenting haemorrhagic symptoms, but there is also serious malaria that can cause this type of symptom, or typhoid fever," a WHO official based in Kinshasa.

"We're still waiting for biological confirmation to find out what kind of disease this is," said Amandine Colin of MSF, which has teams in the affected territory of Boende, in Equateur province.

Samples have been taken to be examined at the National Institute of Biomedical Research, as well as a specialised laboratory in Gabon, Numbi said, adding that the results should come within days.

Country-wide quarantines

The outbreak of the Ebola virus in west Africa is the largest ever, with outbreaks in Liberia, Guinea, Sierra Leone and Nigeria since March.

The disease continues to spread in West Africa, with 142 more cases recorded, bringing the new total to 2,615, Who stated on Friday in an AP report.

Most of the new cases are in Liberia, where the government was delivering donated rice to a slum where 50,000 people have been sealed off from the rest of the capital in an attempt to contain the outbreak.

On Friday, the Central African country of Gabon announced it was barring all flights and ships from Ebola-stricken countries. South Africa already announced a travel ban for non-citizens from these countries "unless the travel is considered absolutely essential".

Senegal closed its borders with Guinea, and is barring air or sea travel from Sierra Leone and Liberia. Cameroon has barred flights from Nigeria.