Mali, according to the UN, is limiting access to the murder location.

The UN is concerned that Malian authorities have denied UN human rights investigators access to a town where hundreds of people have been killed.

The UN Human Rights Office said in a statement that "we are highly concerned that Malian authorities have still not permitted UN human rights investigators access."

"Time is of the essence to ensuring responsibility and fast, effective justice for victims," it writes, noting that it requested access to the crime scene on April 1.

During an operation against insurgents last month, the Malian military and their Russian allies are accused of slaughtering civilians.

During the raid on the town of Moura in Mali's central Mopti area on March 27-31, at least 300 people are thought to have been killed.

Human Rights Watch, the United States, the European Union, and the United Nations have all called for an independent investigation into the killings.

The Malian army maintains that those murdered were Islamist combatants and that the claim of a massacre is an attempt to smear its reputation.

Mali's army has carried out a successful operation, according to a Russian foreign ministry spokeswoman.

The junta in Mali denies that mercenaries from Russia's Wagner outfit are assisting it in fighting terrorists.

Millions of people have been affected by a decade-long insurgency in the country, which has also enveloped other countries in the region.