REUTERS - Civilians on both sides of the front lines in eastern Congo are being killed, raped and abducted by both Tutsi rebels and government troops despite a lull in fighting, human rights campaigners said on Monday.

After weeks of combat which displaced a quarter of a million people, rebel fighters loyal to renegade Tutsi General Laurent Nkunda pulled back from some frontline positions last week in Democratic Republic of Congo's North Kivu province.

A ceasefire declared by Nkunda in late October, when he halted his advance on the provincial capital Goma, was ratified on Nov. 16, leading to a week of relative calm.

But New York-based Human Rights Watch (HRW), citing reports from victims, witnesses and local rights activists, says abuses against civilians, including killings, rapes and kidnappings, have gone on in both rebel- and government-controlled zones.

"We are getting reports of killings in Kiwanja and disappearances in other locations committed by both sides that indicate serious human rights violations are ongoing," HRW Congo researcher Anneke Van Woudenberg told Reuters.

Nkunda's National Congress for the Defence of the People (CNDP) rebels took Kiwanja and Rutshuru in their advance. Rights activists accused the rebels and rival pro-government Mai-Mai militia of tit-for-tat killings of dozens of civilians.

The U.N. peacekeeping mission in Congo (MONUC) called the killings, along with recruitment of child soldiers, war crimes.

The CNDP denied its fighters were responsible for the murders in Kiwanja and blamed the Mai Mai militia.

In a letter to Nkunda last week, MONUC chief Alan Doss, demanded that he put an end to abuses against civilians.

"(The UN) continues to receive pertinent information relative to grave violations of international humanitarian law and human rights attributed to your elements," Doss wrote.