However, they have failed to identify the cause of the current outbreak.

The World Health Organisation (WHO) said the symptoms of the haemorraghic fever were not in keeping with Ebola, which kills 80% of its victims.

Most of the dead were men, they had respiratory complications and people who had washed the dead bodies had not become infected.

Also, only one doctor had become sick despite several treating patients with protection.

Health officials initially suspected Ebola was behind the deaths because victims succumbed to a high fever and massive haemorrhaging followed by death within 48 hours.

The first case occurred in January in the Durba area in northeastern DCR.

Washing the dead

The worst outbreak of Ebola, which was first identified in 1976, was in the DCR, then Zaire, in 1995. Around 350 people died.

Many were infected after washing the bodies of dead people in preparation for their funerals.

The WHO said the current outbreak in DCR had not spread as widely as had been feared and there appeared to be a link with gold-mining.

Many of the men who have died are gold miners, working in extremely unhygienic conditions.

The WHO said it was unlikely the deaths were linked to poisoning from mercury used to treat gold.

But Dr Ray Arthur of the WHO said: "They are gold miners and one has to consider the possibility just on that basis that they may be exposed to whatever is causing the illness in the mines."

Blood samples from the victims are being analysed by the National Institute of Virology in South Africa.

Attempts to find out the cause of the outbreak have been made more difficult by the fact that it has occurred in areas under control by the Tutsi rebels, who are trying to overthrow President Laurent Kabila.

Rebels

The UN has called on all parties in the conflict to support efforts to investigate the outbreak.

The leader of the main rebel group, Ernest Wamba dia Wamba, agreed to allow doctors from the DCR capital Kinshasa to the area to study the deaths.

Meanwhile, Zambia has put four provinces on the border with DCR on a health alert.

Doctors and an epidemiologist have been sent to the border town of Kaputa where at least 28,000 DCR refugees are camped.