Authorities in Mali have found a mass grave believed to contain bodies of soldiers missing since last year

The nation's leading prosecutor has said the find should lead to murder being added to the list of charges being brought against a former junta leader.

General Amadou Sanogo, who led a March 2012 coup that plunged Mali into chaos, was arrested and charged with complicity in kidnapping last week.

Judicial sources said 21 bodies had been found overnight in the village of Diago near the southern garrison town of Kati, about 30 kilometres north of the capital Bamako.

A reporter at the scene said police the shallow grave is being guarded by police after Malian officials removed the corpses it contained.

Mali's chief prosecutor Daniel Tessougue said all signs pointed to the bodies found being those of 21 soldiers who disappeared after a failed April 2012 "counter-coup" by soldiers loyal to ousted President Amadou Toumani Toure, but the formal identification process would have to be finalised.

"We will add murder to the charges (against Mr Sanogo). If we find there are signs of torture we will add that too," he said.

The case against Mr Sanogo and several other soldiers is part of efforts by President Ibrahim Boubacar Keita to assert civilian control over the army, accused by human rights groups of excessive violence and torture during a chaotic 18 months when rebels occupied northern Mali last year.

Mr Sanogo's coup was popular as many Malians were frustrated at underdevelopment and high levels of corruption under Mr Toure. His star has waned in recent months but 12 policemen were wounded in clashes with pro-Sanogo demonstrators in Kati this week.