A cholera outbreak in Democartic Republic of Congo's eastern city of Goma is raising fears of an epidemic among tens of thousands of refugees in camps, aid workers said on Thursday.

Fighting between government soldiers, Tutsi insurgents, Rwandan Hutu rebels and local Mai Mai militia has forced more than 370 000 to flee villages in North Kivu province this year. More than 45 000 displaced people now live in five overcrowded camps on the edge of Goma where aid agencies are struggling to maintain minimum hygiene standards.

The medical charity Medecins Sans Frontieres (MSF) said it recorded 533 cases of cholera at health centres it supports, in both the camps and Goma, over the past six weeks.

"The main crisis is in the camps around Goma," said Patrick Lavand'homme, head the UN Office for the Coordination of Humanitarian Affairs in Goma.

Some 189 cases were reported between October 24 and 28, mostly in the camps for the displaced, he said.

Cholera, spread mainly through contaminated water or food, causes severe diarrhoea and fever, and can kill within 24 hours without proper treatment. It is common in North Kivu and outbreaks in Goma are an annual occurrence. Three people have died from the disease so far, MSF said.

MSF-France's head of mission in eastern Congo Leo Jansen said that while the outbreak was manageable, it could soon flare out of control because refugees continue to flood in.

"They're in a bad situation. They're susceptible to cholera. We've seen the number of cases double inside Mugunga (camp) in recent weeks," he told Reuters.

"We are fearing that the outbreak could be bigger than in other years."

Aid agencies have stepped up preventative measures, including educating camp residents about proper hygiene and increasing the supply of water to the camps. In 1994, nearly 1-million mainly Hutu refugees fled to Goma from Rwanda fearing reprisals following a genocide that killed some 800 000 Tutsis and moderate Hutus.

The sudden influx provoked a major humanitarian disaster and more than 50 000 people died after a cholera epidemic swept through the camps. The arrival of the refugees helped trigger a five-year war in 1998, since when an estimated 4-million Congolese have died from violence or hunger and disease caused by the war.