Rebel leader Laurent Nkunda has threatened to take over the whole of the Democratic Republic of Congo if President Joseph Kabila does not agree to talks on power sharing.
There has been fighting in eastern Congo since August.
President Kabila has already ruled out talks with the rebels, saying they would be unconstitutional.
General Nkunda says his forces have been observing a ceasefire since late last month, but they will fight back when attacked.
The North Kivu region borders Rwanda and Uganda.
African and Western governments are worried the fighting will again draw in Congo's neighbours as occurred during a previous war in 1998-2003. That war eventually involved six African armies.
The DR Congo is a country the size of Western Europe.
