An outbreak of Ebola haemorrhagic fever has claimed possibly as many as 31 lives in the northeast of the Democratic Republic of Congo since May, Health Minister Felix Kabange Numbi said Thurday.

An epidemic was officially declared on August 17 in Orientale Province, when nine deaths were reported, almost all in the town of Isiro.

But Numbi said an international committee for technical and scientific coordination in the fight against had carried out retrospective research to find previous cases, which raised the death toll.

The committee estimates that the epidemic probably began in May, and that so far 69 cases had been registered, including among health personnel, Numbi added.

Out of the 31 deaths, nine were confirmed in laboratory tests to be due to Ebola, he said.

The disease, named after a small river in DR Congo, is fatal in about 50 to 90 percent of cases, with victims bleeding from body orifices before dying in the most severe instances.