Congolese Health Minister Mashako Mamba said on Friday that the symptoms of the disease were similar to those of the deadly Ebola virus - but added that no testing had yet been done.

The World Health Organisation said several symptoms - such as respiratory problems - did not correspond with those of Ebola.

Ebola is characterised by internal and external bleeding, and kidney and liver failure.

A team from the Medecins Sans Frontieres medical charity is reported to have gone to the region.

The WHO has said it was working with MSF to fly out samples to Johannesburg for analysis.

The WHO said 63 people out of 68 cases had died of the viral haemorragic fever since the beginning of the year. Fifty-eight were men aged 15-35.

Mr Mamba said the country was confronted by an epidemic. He told a news conference that the disease had killed 50 people in the north-eastern town of Durba between mid-January and mid-March.

There have also been reports that the virus is spreading towards Sudan, after starting in the rebel-held northeast.

No vaccine exists for the Ebola virus

Dr Stephen Toovey, director of the independent information service Medinfo, said the disease had been reported in Faradje - some 50km from the Sudanese border.

"In this situation, that is very little. There is a very real danger of it spreading to Sudan," he said.

The Ebola virus is named after a river in north-western Congo, where the disease was first identified in 1976. A second epidemic in the Congolese city of Kikwit in 1995 caused at least 245 deaths.