The Democratic Republic of Congo army is using heavy artillery to continue its offensive against rebels loyal to dissident General Laurent Nkunda.
The army is advancing on two fronts
After taking control of the town of Mushake on Wednesday, Congolese troops have moved further north. Intense fighting is underway in Kingi village.
Aid workers fear that the army's use of imprecise long-range weaponry could lead to civilian casualties.
Some 200,000 people have fled fighting in eastern DR Congo, the UN says.
The BBC's Arnaud Zajtman in the regional capital, Goma, says the war has entered a new phase, with the army entering territory controlled by Gen Nkunda's forces.
He says the army is approaching rebel positions on two fronts and is also using tanks.
But our correspondent says their victory is not guaranteed.
President Joseph Kabila said in his annual state of the nation address to both houses of parliament that the uprising would be ended soon "whatever the cost".
Our correspondent says that some 10,000 people are living in a camp near Gen Nkunda's base and there are fears he may use them as human shields.
They are mostly ethnic Tutsis - the community which Gen Nkunda says he is protecting from Rwandan Hutu rebels in the area.
The US has urged Gen Nkunda to go into exile in order to end the fighting but his spokesman denied reports that he had agreed.
"Gen Nkunda cannot make that decision without consultations, that is propaganda meant to demoralise our fighters," Brigadier Kakolele told the BBC Swahili service.
"He is Congolese and here to stay."
He also said the rebels were fighting back against government forces.
The UN mission in DR Congo (Monuc) has been providing logistical support to the Congolese army and on Tuesday said that as a last resort it would also "provide fire support" against the rebels.
The 15,000 UN soldiers in DR Congo are tasked with securing peace after a five-year conflict officially ended in 2002.