The body of Zawadi Katsuva, 49, is carried to a grave Friday in the village of Kiwanja, 56 miles north of Goma, eastern Congo. Katsuva's brother, William Cambale, said that 20 Congolese rebels came to the village, asked for money, then killed him. Clashes between Congo's army and rebels broke out briefly just outside the provincial capital of Goma on Friday as a peace summit aimed at halting the crisis opened in Kenya, the United Nations said.

Goma, Congo ? Reports that Angolan troops joined Congolese soldiers battling rebels near the city of Goma raised new fears the conflict could spread in the region, but the U.N. chief holding a peace conference in nearby Nairobi denied the reports.

New clashes between the army and rebels erupted outside Goma near Kibati, where about 45,000 refugees from the rebellion in mineral-rich eastern Congo have taken refuge. Thousands fled toward the relative safety of Goma.

The French aid group Doctors Without Borders reported fighting in the towns of Rutshuru and Kiwanja, where the charity tried to send staff who had to turn back. The aid group said Rutshuru hospital was full of displaced civilians.

Congo asked Angola for support Oct. 29, as rebels led by Tutsi former Gen. Laurent Nkunda advanced toward Goma, capital of North Kivu province near the Rwandan border. Nkunda called a unilateral cease-fire last week when his forces reached the city outskirts, but the truce has crumbled.

A U.N. official and a Uruguayan peacekeeping officer said Friday that an unspecified number of Angolan troops arrived four days ago. The two officials spoke on condition of anonymity because of the subject’s sensitivity.

But U.N. Secretary-General Ban Ki-Moon said he knew nothing about Angolan troops in Congo.

“I have no information about the Angolan troops participating in this at this point,” Ban said at a news conference called after a peace summit in Nairobi, Kenya.

He then asked U.N. envoy in Congo Alan Doss, who replied “No, Secretary-General … I have no direct independent confirmation of that report.” In New York, U.N. Assistant Secretary-General for Peacekeeping Edmond Mulet suggested some people may have mistaken Congolese government troops who had trained in Angola, and therefore spoke Portuguese, for Angolan troops.

The involvement of Angolans could spread the conflict beyond Congo’s borders. Neighboring Rwanda likely would consider Angolan troops a provocation. Rwanda’s Tutsi-led government is accused of supporting the Congolese rebels.

Congo’s 1998-2002 war drew in more than half a dozen African nations, including Angola and Rwanda, which profited from the vast country’s wealth of diamonds and other minerals.

Meanwhile, African leaders criticized the U.N. peacekeeping force in Congo – the world’s largest – for failing to protect civilians and end the violence that is convulsing eastern Congo.

Ban, holding the peace summit with Congolese President Joseph Kabila and six other African leaders, warned the “crisis could engulf the broader sub-region.”

“We must put the cycle of violence behind us,” Ban said, while calling for the Congolese army to be strengthened to respond to the situation.

Kabila spokesman Kudura Kasongo said the U.N. mission in Congo, known as MONUC, has not fulfilled its mandate. “If they have failed, why are we being left alone with that burden?” Kasongo asked.