The most affected IDPs were in Kiwandja in Rutshuru territory, about 70km north of Goma, the provincial capital, and in Nyanzale, 60km north of Goma.
"FARDC [the Army] abandoned their headquarters in Nyanzale and a large number of displaced civilians are on the road, fleeing the fighting, which broke out at 7.30am on Thursday [6 November] between FARDC and CNDP [Congrès national pour la défense du peuple]," Madnodje Mounoubai, a spokesman for the UN Mission in Congo (MONUC), told IRIN.
The fighting occurred one week after Nkunda declared a unilateral ceasefire just as his fighters were several kilometres from Goma.
Francesca Fontanini, external relations officer for the UN Refugee Agency, UNHCR, in Goma, said a "massive food distribution" got under way on 5 November in six UNHCR-run camps for tens of thousands of IDPs.
"A four-truck UNHCR convoy carrying 33 tonnes of various aid items, including plastic sheeting, blankets, kitchen sets and jerry cans crossed Wednesday [5 November] from Rwanda into Goma, the capital of the conflict-hit province in eastern DRC," she said. "The aid, from regional emergency stockpiles in Tanzania, was scheduled for immediate distribution."
According to Fontanini, the food distribution was the first in North Kivu since serious conflict between the Congolese army and Nkunda's fighters sent tens of thousands of displaced people fleeing for their lives. Many IDPS ended up in the six camps.
"The aid operations were made possible following a ceasefire and relative calm over the past few days but reports of fresh fighting on Tuesday [4 November] between the pro-government Mai-Mai militia and Nkunda's forces in the Rutshuru region are threatening to restrict the movement of humanitarian agencies once more," she said.
Earlier in the week, Fontanini said, UNHCR had helped to improve shelter and sanitation facilities at the crowded Kibati IDP camp, which is close to Goma and whose population grew from 15,000 to some 65,000 people in the space of a few days.
The biggest obstacle for humanitarian workers in North Kivu, she said, was the reduced or non-existent access to the most vulnerable civilians.
More than 250,000 people have been displaced since the fighting resumed in August in North Kivu.