BY TOM MILES
GENEVA - A Ugandan Islamist rebel group committed human rights abuses in the eastern Democratic Republic of Congo last year that may amount to war crimes and crimes against humanity, according to a U.N. report published on Wednesday.

The Allied Democratic Forces killed at least 237 civilians in the last quarter of 2014, including 65 women and 35 children, the U.N. human rights office said in a statement.

"In total, ADF combatants attacked 35 villages. Attackers used machetes, hammers and knives, among other weapons, to wound or execute civilians. Some had their throats slit, were shot at while trying to flee, or were burned alive in their homes."

Civil society groups in eastern Congo said the ADF had killed 13 people with machetes and hatchets in two overnight assaults over the last week.

"These violations, which were both systematic and extremely brutal, may amount to war crimes and crimes against humanity," the U.N. statement said.

Dozens of armed factions are active in Congo's chaotic east, continuing to fight for control over its vast reserves of gold, diamonds and tin following a 1998-2003 war that killed millions and drew in more than a half dozen neighboring countries.

The U.N. report said that civilians in the Beni area where the ADF attacks occurred remain extremely vulnerable to violence. This threat, it added, had spread to the Irumu region, also in the east of the vast central African state, where violations by ADF combatants have been reported this year.

The Congolese army launched a major operation against the ADF last year and says it has dramatically weakened the group.

ADF leader Jamil Mukulu was arrested last month in Tanzania. Congo and Uganda have both asked Tanzania for his extradition.

“I welcome these initial steps towards justice but urge the authorities to redouble their efforts to hold to account all those implicated in the series of truly horrendous crimes that ravaged the Beni area last year,” U.N. human rights chief Zeid Ra’ad Al Hussein said in the statement.

The U.N. report said Congolese armed forces had also violated international humanitarian and human rights law and at least 300 people, including at least 33 members of the armed forces, had been arrested in connection with the Beni massacres.

Civilians continued to come under regular attack in the region. The Congolese army blamed ADF fighters for an ambush on U.N. peacekeepers last week that killed two and wounded 13 Tanzanian soldiers.