The U.N. has repeatedly accused Malian soldiers of summarily executing civilians and suspected militants over the course of their decade-long fight against groups linked to al-Qaeda and Islamic State.
Mali's military government, which took power in a 2020 coup, has been battling Islamist insurgents with the help of private military contractors belonging to Russia's Wagner group.
The alleged April massacre took place on market day in Hombori municipality, in the central region of Douentza, after a Mali military convoy hit an improvised explosive device.
The massacre victims included a woman and a child, the U.N.'s peacekeeping mission MINUSMA said in a quarterly report on human rights violations in the insurgent-hit West African country.
It did not specify the nationality of the foreign military personnel accompanying local troops.
Some 500 people were briefly detained during the military operation prompted by the explosion, but most were later freed. Days later, a single Malian soldier allegedly executed 20 of the 27 civilians still held at the military camp in Hombori, according to the U.N.
Mali's military spokesman did not immediately respond to a request for comment.
Authorities have previously denied accusations that soldiers tortured civilians held in Hombori, the report said.
In the report, MINUSMA documented 317 civilian deaths between April 1 and June 30, 42 percent lower than the 543 registered during the first quarter of 2022.
While insurgents carry out most of the abuses, Malian defense and security forces were responsible for just over a quarter of violent acts against civilians recorded during that period, according to the report.
Mali's military has in some cases acknowledged its forces were implicated in executions and other abuses. But few soldiers have faced criminal charges.
Authorities have banned U.N. investigators from a site where Malian troops and suspected Russian fighters allegedly executed around 300 civilian men during a military operation in March.
Both Mali and Russia have previously said the Wagner group is not made of mercenaries but trainers helping local troops with equipment bought from Russia.