France and its African partners must work together to wipe out Islamist militants in the volatile Sahel region, President Emmanuel Macron said at the opening of a summit in Mali's capital Bamako on Sunday.

At the meeting, leaders of the G5 Sahel bloc - Mali, Burkina Faso, Mauritania, Niger and Chad - were expected to launch a new multi-national force aimed at combating Islamist militants and illegal activity in the vast region.

"Every day we must combat terrorists, thugs, murderers ... who we must steadfastly and with determination eradicate together," said Macron, who was making his second visit to Mali since taking office in May.

Islamist militant groups, some with links to al-Qaeda, seized control of Mali's desert north in 2012.

While they were driven out of major cities and towns a year later by a French-led military intervention, they continue to carry out attacks against UN peacekeepers, Malian soldiers and civilian targets.

The violence has spilled over into neighbouring countries in West Africa's Sahel region and Paris has deployed thousands of French troops to combat Islamists as part of a cross-border operation known as Barkhane.