Bertrand Bisimwa, a spokesman for Nkunda's National Congress for the Defence of the People (CNDP), told AFP a meeting had been planned and should take place later on Saturday or on Sunday.
Obasanjo could see Nkunda in the rebel stronghold of Rutshuru, about 75km of Goma, he added.
Fighting between the army and fighters loyal to Nkunda, who claims to be fighting to protect ethnic Tutsis in the region, has displaced at least 250,000 people.
At least 100 people have been killed since fighting broke out in September, despite the presence of about 17,000 UN troops - the largest UN peacekeeping force in the world.
Obasanjo's diplomatic mission comes amid reports of renewed fighting between government troops and rebel fighters in Kabasha, a village around 110km north of Goma.
Colonel Jean-Paul Dietrich, a UN spokesman, said the exchange of fire lasted for about 10 minutes and that it was "not clear who started it".
He said UN peacekeepers had launched patrols in the area.
On Friday, Obasanjo met Jose Eduardo Dos Santos, the Angolan president, who assured him no Angolan troops were in DR Congo, despite numerous reports of Angolans helping Congolese forces.
There are fears the country could slide back into a ruinous war such as the one in 1998-2002, that drew in more than half a dozen African nations and reduced DR Congo to rival fiefdoms.
Fighters backed by Uganda and Rwanda seized vast swaths of territory rich in coffee, gold and tin in the east. Angola and Zimbabwe sent tanks and fighter planes to back DR Congo's government in exchange for access to lucrative diamond and copper mines to the south and west.
Eastern Congo has been unstable since millions of refugees spilled across the border from Rwanda's 1994 genocide, which saw more than 500,000 ethnic Tutsis and moderate Hutus slaughtered.
Civilians have reported numerous cases of abuse.
On Friday, women took to the streets in the region's capital city Goma to protest against rapes reportedly taking place in the ongoing conflict.
One woman claimed to have been raped by government-backed Mai Mai militia men near the town of Kanyabayonga, 100km north of Goma.
|Those displaced are now battling
hunger and diseases [AFP]
Junissa Mulambe said she and others were molested while their husbands were forced to watch.
"We ran from the village because of the war and then we went in the bush somewhere to hide and there were three Mai Mai who came... They took our husbands and tied them with ropes and then they started doing bad things to us and our husbands were looking," she said.
Luis Moreno-Ocampo, the prosecutor of the International Criminal Court, said he was investigating violence in eastern DR Congo, where he added that "a multiplicity of crimes", including rape and murder, are being committed by rebels groups including those loyal to Nkunda.
In Brussels on Friday, Bernard Kouchner, the French foreign minister, said the European Union will consider "rapidly setting up a humanitarian logistics mission" to help people in the eastern area of the country."
Both the EU and the UN have been criticised by aid groups for their slow and inadequate response to the crisis in Congo.