Government forces have been fighting troops loyal to Laurent Nkunda, who claims he is defending minority Tutsis from other ethnic groups and armed movements around Karuba.
He left the army and formed his own militia after the Congolese conflict ended in 2002 and is named in an international arrest warrant for alleged war crimes.
Rene Abandi, a spokesman for Nkunda, said that government forces had shelled their positions and that they had taken their wounded back to their bases. He was not able to give casualty figures.
|"The ceasefire was broken |
by the government and we have been under constant attack"
General Laurent Nkunda
The United Nations peacekeeping force in the region (Monuc), confirmed that government forces (FARDC) had made progress after two days of fierce fighting.
"Karuba was taken by the FARDC yesterday. Nkunda's forces are gathered around the [neighbouring] village of Ngengwi," Major Prem Tiwari, Monuc spokesman, said.
The two sides agreed to stop fighting and try to restart talks about a month ago, but new clashes were reported in late September and on Monday, Nkunda announced a fresh offensive effectively breaking the truce.
However, Nkunda says that the government is responsible for restarting the fighting.
"The ceasefire was broken by the government and we have been under constant attack," he told The Associated Press on Tuesday.
The UN peacekeeping force says about 6,000 families have fled to Mushake, a town about 90km north of Goma, in recent days.
Since January, between 400,000 and 500,000 people have been displaced by fighting in the province, Louis Igneault, a spokesman for the UN's office for the co-ordination of humanitarian affairs, said.
The renewed violence has made it even more difficult for UN aid workers to get food to thousands of desperate civilians.
"This is a serious blow. The fighting restarted just as we were trying to relaunch distributions outside Goma. We'll have to re-evaluate now based on what is happening," Aya Shneerson, World Food Programme director in North Kivu, told Reuters news agency.
A WFP convoy has been attempting to get aid to the district of Masasi for more than a month.
The group reported hearing heavy machine gun and artillery fire as well as seeing an exodus of civilians as they travelled through the province.