UN rights chief Zeid Ra'ad al Hussein says a militia linked to the government has committed a string of ethnically-motivated attacks in recent months, including cutting off toddlers' limbs and stabbing pregnant women.
The United Nations Human Rights Council opened an investigation on Friday into killings and other atrocities in the Kasai region of the Democratic Republic of Congo.
The 47-member Geneva forum adopted by consensus a resolution brought by African countries that also called on the government of President Joseph Kabila to cooperate with the team of international experts.
UN rights chief Zeid Ra'ad al Hussein, who is to name the fact-finding experts, had called repeatedly for the inquiry into events in Kasai, an opposition stronghold.
"We fully support the establishment of an international investigation by the Human Rights Council as a step forward in identifying the perpetrators of gross violations and bringing them to justice," Hussein said in a statement.
His office counted on the "full cooperation" of the government and on the experts having unfettered access to all sites, files, people and places.
"The team will conduct investigations in a fully independent manner, in accordance with international standards, as mandated by the Council," he declared.
Hussein told the council on Tuesday that a militia linked to government has committed a string of ethnically-motivated attacks in recent months, including cutting off toddlers' limbs and stabbing pregnant women.
Kinshasa has been fighting insurgents in Kasai since last August, triggering fears of a wider conflict in the large central African country, which is a tinderbox of ethnic rivalry and competing claims over mineral resources.
Local activists said on Thursday that at least 12 people were killed in heavy fire fights between the army and militia fighters in and near the city of Beni, and several students sitting exams were wounded in an explosion at a school.
Activists welcomed the probe, which was agreed on the last day of the Council's three-week session.
It "brings hope of uncovering the truth about the horrific violence in the Kasai region since August, a step toward justice for thousands of victims," Laila Matar of Human Rights Watch said in a statement.
The New York-based group called for Congolese authorities to ensure unhindered access for the team.