Security and community sources in Mali says more than 40 civilians were killed over the weekend in an attack by armed men on camps in the north-eastern Menaka region.
They reportedly arrived on motorcycles and targeted camps mainly housing members of the Daoussahak community.
The community's executive bureau has blamed the killings on the Islamic State group.
The government-aligned armed Movement for the Salvation of Azawad (MSA) reportedly has its origins in the area.
A security source based in Gao said the massacre occurred "in retaliation for military operations carried out in the area recently and for attacks by the MSA".
For its part, the Malian army said it had conducted operations on Saturday, about 65 kilometres south-west of Menaka.
Officials said it had struck "a major base housing several terrorist elements and military equipment".
Mali has been plagued since 2012 by a security crisis pitting the army against jihadist fighters, Tuareg separatist groups, and criminal gangs.
Since back-to-back coups in 2020 and 2021, its military leaders have turned to Russian paramilitary group Africa Corps for support.
Human Rights Watch, meanwhile, in a report on Monday accused Mali’s armed forces and its Russian backers of killing scores of civilians in recent months.
It says “apparent indiscriminate” drone strikes and other abuses are part of a ramped-up offensive against insurgents.
This follows nationwide attacks in April this year by the regional al-Qaeda affiliate, known as JNIM, and by Tuareg-led separatists.
Mali's defence minister was killed during the 25 April attacks which hit multiple towns and cities, as well as the main airport in the capital, Bamako.