The U.N.'s special envoy on Congo began talks Sunday with the Democratic Republic of Congo's main rebel leader, as heavy fighting erupted in the eastern part of the country.

The U.N. says the fighting broke out just hours before the envoy, former Nigerian President Olusegun Obasanjo, began discussions with rebel leader Laurent Nkunda.    

It was not immediately clear which armed groups were involved in Sunday's fighting in Ndeko, about 90 kilometers north of Goma, the capital of the North Kivu province.  Rebels, the army and pro-government militias are all operating in the region.

Mr. Obasanjo met with the DRC's president, Joseph Kabila, on Saturday. The envoy said the president did not set any conditions for his talks with the rebels.  

As Mr. Obasanjo arrived in the eastern region Saturday, a U.N. spokesman, Lieutenant Colonel Jean-Paul Dietrich, said the army and rebels exchanged fire for about 10 minutes in Kabasha, about 70 kilometers north of Goma.

Government forces and rebels have clashed repeatedly in the eastern DRC since August, in violation of a cease-fire they agreed to in January.  

The United Nations estimates 250,000 people have been displaced since August.

On Friday, the foreign ministers of the DRC and Rwanda met to discuss the crisis. They agreed that Rwandan intelligence officers would join DRC troops fighting Hutu extremists in the eastern DRC.

The presence of Hutu extremists in the DRC is what led Nkunda to begin his rebellion in 2004.  Nkunda says he is fighting to protect Tutsi communities against Hutus who were responsible for Rwanda's 1994 genocide.   

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