The government-backed Bana Mura militia in Congo has committed horrific crimes in ethnically-motivated attacks in the past few months, including cutting off toddlers' limbs and slicing open pregnant women, the U.N. human rights chief said on Tuesday.

"Refugees from multiple villages in the Kamonya territory indicated that the Bana Mura have in the past two months shot dead, hacked or burned to death, and mutilated, hundreds of villagers, as well as destroying entire villages," he said.

"My team saw children as young as two whose limbs had been chopped off; many babies had machete wounds and severe burns," Zeid Ra'ad al-Hussein told the U.N. Human Rights Council in Geneva.