Villagers who fled fighting in this rebel-held town trickled home Thursday to find the bodies of more than a dozen men in civilian clothes in and around mud huts — and accused rebel leader Laurent Nkunda's forces of the slayings.

Nkunda's men wrested control of Kiwanja Wednesday following heavy fighting with a pro-government militia called Mai Mai, one of many signs that the conflict is spreading in eastern Congo and a fragile cease-fire is close to unraveling.

The villagers said rebels had killed unarmed civilians suspected of supporting the Mai Mai, but the rebels said the dead were militia fighters who had been armed.

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A U.N. official said Kiwanja was in fact subjected to two rounds of terror: First the Mai Mai arrived and killed those they accused of supporting Nkunda's rebels, then Nkunda's rebels stormed in, killing men they charged were loyal to the Mai Mai.

The official spoke on condition of anonymity because he is not authorized to speak to reporters.

Human Rights Watch said U.N. peacekeepers nearby had been unable to protect the villagers. It said at least 20 people were killed and another 33 wounded during the battle for the town.

"The U.N. should not leave these defenseless people to be slaughtered by fighters on both sides," said Anneke Van Woudenberg, a senior Africa researcher for the rights group.

North of Kiwanja, rebels captured an army base in Nyanzale Thursday after fighting with the army, the U.N. ated Kiwanja in civilian clothes and began killing villagers who supported the rebels.

Nkunda defected from the army in 2004, saying he needed to protect his tiny Tutsi minority from Rwandan Hutu militias. He has since expanded his mission to "liberating" Congo from an allegedly corrupt government.

Nkunda told The Associated Press on Thursday that his mission justifies the suffering of some 250,000 forced from their homes since he launched an offensive Aug. 28. He also suggested that Congo's army was being bolstered by foreign militias from Rwanda, Burundi and Uganda.

Congo's government has charged Nkunda with involvement in war crimes, and Human Rights Watch says it has documented summary executions, torture, and rape committed by soldiers under Nkunda's command in 2002 and 2004. The rights group said at least 100 civilians have been killed and more than 150 injured since fighting resumed in August.

On Thursday, the director of Community Radio of Kiwanja said rebels killed one of his reporters, accusing him of broadcasting anti-rebel statements.

Jean-Baptiste Kiana said he was at the home of the reporter, Alfred Ndjondjo Victwahiki Munyamariza, when the rebels barged in, forced him out of the house, and shot him in the head in his garden. Kiana said Munyamariza, 25, was killed in plain sight of his wife and toddler daughter.

Fresh fighting between army forces and rebels erupted Thursday north of Kiwanja around the town of Nyanzale, said U.N. peacekeeping spokesman Madnoje Mounoubai. The Congolese army abandoned its positions there and thousands of refugees also fled, seeking shelter near a U.N. base, he said.

Nkunda told The Associated Press that army forces backed by Mai Mai attacked rebel positions miles from Nyanzale before dawn.

"We were attacked three times this morning," he said, speaking from one of his bases in the Mushaki mountains, some 40 miles north of the provincial capital of Goma. "My soldiers have a right to defend themselves. And the best defense is offense."

Later Thursday, the U.N. peacekeeping mission in Congo confirmed that Nkunda's fighters captured the villages of Nyanzale and Kikuku.

Nyanzale is one of three operational army bases in North Kivu provinces. The rebels seized the biggest army base in eastern Congo on Oct. 20.

The army could not immediately be reached for comment Thursday.

The latest violence dealt another blow to a fragile unilateral cease-fire Nkunda declared Oct. 29 as his fighters reached the outskirts of Goma, suddenly halting a lightning advance that forced Congo's army into retreat.

The conflict in eastern Congo is fueled by festering ethnic hatred left over from the 1994 slaughter of a half-million Tutsis in Rwanda, and Congo's civil wars from 1996-2002, which drew neighboring countries in a rush to plunder Congo's mineral wealth.