On May 19 a Malian soldier and at least a dozen other people were killed in violence that occurred during an army patrol through a market.

The army said the 12 were "terrorists" who had been "neutralised", but local residents said they were civilians.

The Malian army is often accused of making arbitrary arrests and carrying out extra-judicial executions in the fight against jihadists.

Following the incident, the UN peacekeeping mission in Mali, MINUSMA, announced at a press conference it would send a special team from its human rights division to inquire into the incident, which occurred in Boulkessi, a town near the border with Burkina Faso.

"The MINUSMA investigation concluded that, on May 19, elements of the Malian battalion of the joint G5 Sahel force summarily and/or arbitrarily executed 12 civilians at Boulkessy's livestock market," the UN mission said late Tuesday, using an alternative spelling of the town's name.

The killings were "in reprisal for the death of one of (the soldiers), who was shot dead by an unidentified attacker," it said in a statement.

The statement said the investigation had been sent to the Malian government.

Backed by France, Mali and four other countries have set up a regional force to fight jihadists in the Sahel but the so-called G5 force has been deploying slowly and struggling with funding.

France intervened militarily in Mali in 2013 to help government forces drive Al-Qaeda-linked jihadists out of the north.

But large tracts of the country remain lawless despite a peace accord signed with ethnic Tuareg leaders in mid-2015 aimed at isolating the jihadists. The violence has also spilled over into both Burkina Faso and Niger.