A Mai Mai militiaman lies dead in the village of Kiwanja in eastern Congo, 6 Nov. 2008

United Nations chief Ban Ki-moon has called for an immediate halt to fighting in the eastern Democratic Republic of Congo, where clashes between rebels and government forces have displaced tens of thousands of people over the past week.

Mr. Ban's statement, issued through his spokesperson, came a day before the secretary-general attends an emergency summit on Congo in Nairobi.

The U.N. mission in Congo says the presidents of seven African countries will attend, including the DRC's Joseph Kabila and Rwanda's Paul Kagame.

Kagame's government is widely accused of supporting the rebels, led by General Laurent Nkunda. Rwanda denies the accusation.

Earlier today, a spokesman for the U.N. mission said Nkunda's men captured the town of Nyanzale in Congo's North Kivu province after army troops fled their positions.

The spokesman accused Nkunda of breaking a ceasefire the general declared last week. The Associated Press quotes Nkunda as saying his forces were attacked three times today and have a right to defend themselves.

After a lull of several days, Nkunda's men have been fighting government troops and pro-government Mai Mai militia in North Kivu since Tuesday.

The Nkunda forces drove militiamen out of another town, Kiwanja, on Wednesday. The U.N. today began investigating reports that Nkunda's men killed a number of civilians in that town.

Aid agencies are scrambling to reach and assist thousands of people displaced by the latest fighting.

General Nkunda says his forces are protecting the minority Tutsi population in Congo against Rwandan Hutu fighters who entered the region after the 1994 Rwandan genocide.

New clashes between the DRC government and Nkunda erupted in late August, following the collapse of a January peace deal.

The U.N. says more than 250,000 people have been displaced from their homes since the new clashes began. It says the total number of people displaced in North Kivu has now topped one million.

The province and nearby areas have remained volatile and prone to clashes between militia groups, five years after the end of Congo's civil war.

Some information for this report was provided by AFP and Reuters.