Mali investigators at scene of mass shooting
The shooting has led to bitter accusations of "mass murder" from Mauritania, and Mali was quick to announce a probe and convey condolences to the families of the slain men.
Army officials initially said troops were forced to open fire on Saturday night after a vehicle failed to stop at a checkpoint, but a Malian soldier later said the shootings were a mistake.
Malian troops are on high alert after hardline militants seized the country's north earlier this year.
In a scathing statement, Mauritania has said those killed were unarmed Muslim preachers, and it demanded to be part of an independent probe.
According to a Malian police official, a team of investigators made up of soldiers, civilians and police arrived on Monday in Niono, close to the town of Diabali where the shooting occurred.
Bamako on Sunday expressed its condolences over the killings, though it has not released the identities of the victims or the shooters. Officials said eight of the men were Malian and eight were Mauritanian.
An official in Nouakchott said Mauritanian troops would be sent to Mali to collect the bodies of the Mauritanian victims.
Since the shootings, Mauritanians have protested outside the presidency in Nouakchott to demand action against those responsible.
The men belonged to the Dawa sect and, according to Mauritania and official sources, had been heading to a religious conference in Bamako.
Diabali is located about 400km north-east of Bamako, hundreds of kilometres by road farther south of the Islamist controlled north of the country.
A Malian soldier on Monday said the mass shooting was an "error".
Corinne Dufka, a senior Africa researcher at Human Rights Watch, called the shooting a "horrific incident".
"The Malian government should suspend the soldiers and their superiors implicated, with a view towards holding all those responsible, regardless of rank," she said. "Justice must be done, and be seen to be done."
Since a disastrous March coup in Bamako, Mali has lost control of all of the arid north and militants have been swift to impose tough sharia law, including stoning people to death.
On Monday, witnesses said militants sliced off a hand and a foot each from four suspected carjackers. – AFP