Nearly 900,000 people have been displaced in Kivu
Renewed fighting in eastern Democratic Republic of Congo has forced the United Nations refugee agency to suspend aid to displaced people.
The UNHCR said hundreds more people have fled their homes because of the latest clashes in North Kivu province.
A week of clashes between the army and fighters from the FDLR of Rwandan Hutu rebels has killed 20 people after three months of relative calm, the UN says.
The army says it is planning a major offensive against the FDLR.
The UNHCR says violence in Kivu has now displaced almost 900,000 people.
The BBC's Arnaud Zajtman in Kinshasa says FDLR fighters attacked a camp where 1,500 people were sheltering on Thursday, forcing them to scatter.
They had earlier briefly abducted three policemen guarding the camp.
EASTERN CONGO ARMED GROUPS
FDLR - Rwandan Hutus
CNDP - Gen Nkunda's
UNHCR officials said most of the displaced people are women and children who are sheltering in public buildings.
Some said their homes had been destroyed and their possessions looted, while some parents said they had lost touch with their children.
The FDLR includes some of those Hutus involved in the 1994 genocide, who fled to DR Congo after Tutsis took power in Rwanda.
Rwanda has long demanded that the FDLR be disarmed, saying they are the cause of the instability in the region.
The displacement in the Rutshuru area, some 70km north of the provincial capital, Goma, comes three months after the signing of an accord in Goma between the government and a different armed group, led by renegade Tutsi General Laurent Nkunda.
Gen Nkunda had also demanded that the FDLR be disarmed - he took up arms, saying he was protecting Congolese Tutsis from Hutu attacks.
A peace agreement in 2003 formally brought years of war to a close, but fighting flared up again in North Kivu that same year.
The UNHCR says there are about 1.3 m displaced people in the Democratic Republic of Congo, while 350,000 Congolese have fled to other countries.