The United Nations mission in Mali says soldiers who are part of a regional counterterrorism force "summarily and/or arbitrarily" killed 12 civilians in vengeance for the murder of a fellow soldier.

The UN mission said on Tuesday that unknown attackers shot a Malian soldier on May 19 at the weekly Boulkessy cattle market.

It said fellow soldiers from the Malian battalion of the G5 Sahel Joint Force retaliated, and civilians were killed.

The mission says it has given its investigative report to Mali's government.

The government has not yet responded.

The mission says it remains concerned about human rights violations in the central region where Islamic extremist groups operate, urging G5 Sahel and Malian forces to conduct military operations in accordance with international human rights law and to protect civilians.