Health workers in the east of the Democratic Republic of Congo say an outbreak of cholera has claimed at least nine lives in a refugee camp.

The first case of cholera - a contagious disease caused by filth and lack of hygiene - emerged three days ago among thousands of people in a makeshift refugee camp, Doctors Without Borders said.

Thousands of people have fled fighting between M23 rebels and government forces backed by UN peacekeepers.

Patrick Wieland, from Doctors Without Borders, said his organisation had set up an isolation clinic tent at Kanyaruchinya on the outskirts of Goma, the capital of North Kivu province.

Wieland said humanitarian agencies were delivering water to the camp but people probably were collecting the water with dirty containers.

He said there were not enough toilets for the people who fled fighting last week in Rutshuru and neighbouring Kiwanja, about 80km north of Goma.

"We're treating people with arms and legs blown-off by grenades and other heavy arms," said Wieland. He also said that for the first time they treated many more civilians than combatants.

'Out in the open'

Al Jazeera's Peter Greste, reporting from Goma, said that locals had told him that 13,500 families had arrived in the past month, displaced by the fighting.

"People have been forced to build their own makeshift shelters - shelters made of twigs, grass and so on and a few leaves," he said.

"Few people have been able to get hold of plastic sheeting from the United Nations refugee agency, but for the most part people are being forced to live out in the open.

"They're saying they have had no food for a month and have [had only] high-energy biscuits a week ago, but since then nothing."

M23 rebels, who take their name from a March 23, 2009 agreement they signed with the Congolese government, last week attacked government troops and UN peacekeepers, firing mortars at the peacekeepers' base at Kiwanja which was surrounded by more than 2,000 displaced people at the time.

Wieland said the fighting was much heavier than any his team has seen in the three-month-old rebellion.

He said that since April, Doctors Without Borders has treated more than 500 people hurt in the conflict.

Congo's army now controls only the city of Goma and the village of Kibumba, 10km outside Goma. Now the rebels hold all towns going north as far as Rutshuru and are threatening to besiege Goma.

The UN Security Council demanded on Thursday that the M23 halt any advances towards Goma.

In a statement delivered by council president Gerard Araud of France, the Security Council expressed deep concern at the worsening humanitarian situation, especially a surge in the number of refugees.

Araud called on the international community to provide appropriate humanitarian support.