By Emmanuel Braun
KIWANJA, Congo, Nov 6 (Reuters) - Congolese Tutsi rebels went from door to door killing men in an eastern town overnight, residents said on Thursday, but rebel commanders said they had targeted only pro-government militia fighters.
U.S.-based group Human Rights Watch (HRW) accused the rebels of war crimes in Kiwanja, where journalists accompanying U.N. peacekeepers found the bodies of a dozen shot civilians a day after rebels drove pro-government militiamen from the town.
The U.N. peacekeeping force in Congo (MONUC) said rebels seized fresh territory on Thursday, violating a self-declared ceasefire in Congo's violent North Kivu province where Tutsi rebel General Laurent Nkunda launched an offensive 11 days ago.
The U.N. has its largest peacekeeping force -- 17,000 strong -- in Congo. But commanders say they cannot be everywhere in a vast, violent country the size of Western Europe which despite huge mineral wealth has only 600 km (375 miles) of paved roads.
A stench of death hung over Kiwanja when journalists and U.N. troops entered. Most of its 30,000 inhabitants fled in panic during fighting on Tuesday and Wednesday.
At least a dozen bodies of adult males, five in one house alone, were visible among the mud-walled and tin-roofed homes, a few of them burned, apparently hit by rockets or grenades.
"They knocked on the doors, when the people opened, they killed them with their guns," said Simo Bramporiki, aged around 60, who said his wife and child were killed during the night.
The International Criminal Court's prosecutor warned this week the court was closely watching the latest flare-up of a conflict that traces its origins to Rwanda's 1994 genocide.
A distraught woman, crying hysterically, asked journalists to "come and see the five dead bodies in my house". One was that of her husband. Two more bodies lay outside. Rebel fighters boasted to reporters that they had killed many Mai-Mai militia.
Journalists asked the U.N. peacekeepers, who have a base nearby, why they had not intervened. They did not reply.
"SCREAMS IN THE NIGHT"
"The killing of civilians, the destruction of camps, the forced return of displaced people, and the forced evacuation of towns are all war crimes," HRW researcher Anneke Van Woudenberg said. "People in Kiwanja heard screams throughout the night."
There was nothing, neither uniforms nor weapons, to indicate the dead had been fighters. Some wore work overalls.
But Nkunda denied his men had killed civilians.
"It was against the Mai-Mai (militia) and many were in civilian dress," he told Reuters by telephone. Rebel commander Major Muhire said Mai-Mai attacked first: "Last night we were attacked by the Mai-Mai and we reacted. That's all."
MONUC military spokesman Lt-Col Jean-Paul Dietrich, said: "Even if they were (Mai-Mai) fighters and surrendered, and were then killed, that would be a criminal act".
Dietrich told Reuters that Nkunda's rebel forces had also occupied other villages about 80 km (50 miles) north of the North Kivu provincial capital Goma. Nkunda advanced to the outskirts of Goma last week, before declaring a ceasefire.
"They have taken Nyanzale and Kikuku, therefore breaking their own declared ceasefire. Now it's clear they are trying to have a territory completely under their control," Dietrich said.
Nkunda said his forces were maintaining the ceasefire.
Aid agencies scrambled to provide food and medical care to 200,000 refugees crammed in camps around and just north of Goma.
But relief workers say that many of over 1 million displaced civilians in North Kivu are out of reach -- cut off by fighting, hiding in the bush or isolated in rebel or militia-held zones.
The latest fighting around Rutshuru has worsened a humanitarian situation already described as "catastrophic" by aid agencies in a country where more than 5 million people have died in a decade from conflict, hunger and disease.
U.N. Secretary-General Ban Ki-moon, on his way to a regional summit on the crisis to be held in Nairobi on Friday, called for all forces to return to positions they held at end-August.
Ban has asked the Security Council to approve a "surge" of 3,000 extra peacekeepers for Congo, but in the midst of a global financial crisis U.N. officials say that could take months.
Ban, as well as the top U.S. diplomat for Africa, Jendayi Frazer, will meet the presidents of Congo and Rwanda in Nairobi.
Ban has said he will urge Congolese President Joseph Kabila to speak with Nkunda. Kabila's government has refused to talk directly to the rebels, who say otherwise they will attack Goma.
Congo and Rwanda have accused each other of supporting feuding rebel and militia groups in east Congo.
Nkunda says his 4-year-old revolt aims to defend Congolese Tutsis and accuses Kabila's army of backing Rwandan Hutu rebels in Congo who took part in Rwanda's genocide. Congo has accused Tutsi-led Rwanda of backing Nkunda, which Kigali denies.
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(Additional reporting by Joe Bavier in Kinshasa and Hereward Holland in Goma; writing by Alistair Thomson and Pascal Fletcher;editing by Michael Roddy)