The bodies of 29 Mauritanians and four Malians were found near the village of Robinet El Ataye in the Segou region, where 33 civilians had been beaten and taken away on March 5, a Panel of Experts on Mali said in a report to the UN Security Council late last month.

A diplomatic source in New York told AFP that the white soldiers were paramilitaries of Russia's Wagner group.

The civilians' disappearance stoked friction between Mali and Mauritania at the time.

Nouakchott accused the Malian army of "recurrent criminal acts" against Mauritanian citizens in the border region. Bamako said there was no proof its army was involved.

The two countries in mid-March launched a joint investigation but its results had not yet been published as of early August.

Western countries say Russian paramilitaries in Mali are mercenaries from the controversial Wagner group while Bamako describes them as "instructors" for its security forces.

The Malian army has conducted numerous military operations to "hunt down" jihadist groups in the Segou and Mopti regions of central Mali since the beginning of the year.

Its soldiers have been accused of abuses on several occasions by NGOs.