Nairobi/Kinshasa - Around 30,000 people fleeing fierce battles between Congolese troops and Tutsi rebels are pouring into refugee camps near the eastern city of Goma, the United Nations refugee agency UNHCR said Wednesday, as the rebels appeared to push back government forces.

UN helicopter gunships and armoured vehicles have been supporting Congolese troops north of Goma, the capital of North Kivu province, as renegade Tutsi general Laurent Nkunda's troops press toward the town.

Nkunda's National Congress for the Defence of the People (CNDP) says it has driven the Congolese army back from the town of Kibumba, which lies about 20 kilometres north of Goma.

UNHCR said that 20,000 from another camp at Kibumba were amongst those arriving at a camp for the country's refugees at Kibati, 10 kilometres north of Goma.

The top United Nations envoy to the Democratic Republic of Congo has appealed for more soldiers as the rebel forces threaten to overwhelm government troops and UN peacekeepers.

The UN peacekeeping mission in the DR Congo (MONUC) has only 6,000 troops in the area - out of a total of 17,000 in the sprawling country - and they are being stretched to the limit.

Alan Doss, the head of the UN mission in DR Congo, said in a video conference Tuesday that he needs urgent reinforcements, but that his soldiers would try to prevent major towns falling to the CNDP.

Doss said that UN attack helicopters had fired on CNDP forces near Kibumba on Tuesday. He also warned that the CNDP forces has split into smaller unit in an attempt to infiltrate Goma.

The CNDP has also attacked the town of Rutshuru, 70 kilometres north of Goma, prompting plans to evacuate foreign aid workers based there. However, locals angry at the UN for failing to protect them frustrated the rescue attempts.

"A convoy to evacuate around 50 international humanitarian workers was blocked by local population and some soldiers yesterday," Ivo Brandau, a spokesman for the UN's Office for the Coordination of Humanitarian Affairs (OCHA) in Congo, told Deutsche Presse-Agentur dpa Wednesday.

"They are in the MONUC base in Kiwanja," he added. "We are looking into the possibilities for today."

Angry demonstrators stoned UN compounds in Goma on Monday and Tuesday. The UN mission said peacekeepers were forced to intervene, and that one civilian was killed in the rioting.

However, Doss defended the peacekeepers, saying it was not possible to have "a soldier behind every tree, on every road or in every market."

The CNDP and other groups in January signed peace accords designed to end sporadic clashes that occurred in 2007, four years after the war officially ended.

But the CNDP and government soldiers have been involved in repeated clashes in the eastern North and South Kivu provinces since late August.

UN Secretary General Ban Ki-moon on Wednesday called for an immediate end to fighting.

"This fighting must be stopped, and I am deeply concerned about the civilian casualties as well as the increasing number of internally displaced persons," he said at a press briefing in Manila, where he was attending an international conference on migration.

Ban said he was already consulting with the leaders of Congo and its neighbour Rwanda as well as European and African leaders to help resolve the conflict.

The DR Congo government has accused Rwanda of amassing troops on the border with a view to backing Nkunda and attacking Goma.

Nkunda's troops say they are fighting to protect Tutsis from armed Hutu groups.

Many of the Hutus fled to DR Congo after the 1994 massacre in Rwanda, when Hutu militia and military killed an estimate 800,000 Tutsis and moderate Hutus in the space of a few months.

Aid agencies say well over 100,000 civilians have fled the renewed fighting since August, bringing the number of refugees in North Kivu to almost one million. The agencies warn of an impending humanitarian disaster.

"The numbers of internally displaced are already huge and it looks like it is going to grow," UNHCR spokesman Ron Redmond said.

More than 5 million people are estimated to have died as a result of the long war in the resource-rich nation, most of them due to hunger and disease.

The conflict is often referred to as the African World War owing to the large number of different armed forces involved.

Observers are concerned that the new clashes could re-ignite a wider conflict and plunge the country back into chaos. (dpa)