"Following the allegations of alleged abuses committed against civilians... investigations have been opened by the national gendarmes on the instructions of the defence ministry and veterans to carry out thorough investigations to shed light on these allegations," the military prosecutor said in a statement.

Mali's army announced on April 1 that it had killed 203 militants in Moura, in the centre of the Sahel nation, during an operation in late March.

However, that announcement followed widely shared social media reports of a civilian massacre in the area.

Human Rights Watch said this week that Malian forces and foreign fighters killed 300 civilians in Moura, in what it called "the worst single atrocity reported in Mali's decade-long armed conflict".

Malian forces were operating in tandem with white foreign soldiers, according to HRW, who are believed to be Russian because witness accounts refer to them as non-French-speaking.

Russia has supplied what are officially described as military instructors to Mali.

However, the United States, France, and others, say the instructors are operatives from the Russian private-security firm Wagner.

On Wednesday, independent UN human rights expert Alioune Tine urged an independent and impartial investigation into the events.

In a statement, he called on the Malian authorities to allow the UN peacekeeping mission in Mali, known as Minusma, to perform the investigation.

"The findings must be made public and the alleged perpetrators brought to justice," Tine added.

The rights expert joins the United States, European Union, the UN and the Malian human rights commission in calling for an investigation into the alleged massacre.