Driving cars and motorbikes, the attackers stormed Dioura army camp in the Mopti region at dawn, leaving "many soldiers dead or missing", a military source said.

Separately, a Malian security source spoke of "a heavy toll of at least eight dead".

"There are dead soldiers, others are missing and still others are wounded," he said, but could not confirm reports from local villagers that up to 15 troops had died.

A second military source said the troops had tried to fight off the attackers.

"Our men responded. I saw at least four bodies on the ground. We don't have an exact toll yet but there is a lot of damage," he said.

A foreign security source said local residents estimated at least 15 people had been killed.

President Ibrahim Boubakar Keita, on Twitter, said the Malian people were "united against terrible acts", without giving any death toll.

Once a beacon of democracy and stability in Africa, Mali in recent years has been dogged by a coup, civil war and Islamist terrorism.

Extremists linked to Al-Qaeda took control of Mali's desert north in early 2012, but were largely driven out in a French-led military operation launched in January 2013.

In June 2015, Mali's government signed a peace agreement with some armed groups, but the jihadists remain active, and large tracts of the country remain lawless.

Despite the presence of UN peacekeepers, a strong French military contingent and the creation of a five-nation military force in the region, jihadist violence has not abated in Mali which suffered 237 attacks in 2018, UN figures show.