"Two of our men were killed by terrorists on Saturday night in an attack on one of our checkpoints, 60 kilometres (40 miles) southwest of Gao," a military official told AFP.

The word "terrorists" is regularly used to refer to Islamist militants, in a region struggling against grinding insurgency.

Another military official said two soldiers were killed and another was injured.

They were ambushed as they as moved between positions at the checkpoint, a security official said, also on condition of anonymity.

On Sunday, UN peacekeepers drove over an improvised explosive device (IED) near Douentza, in the centre of Mali, officials said.

Five of the eight hurt were in a serious condition.

IEDs are a favourite weapon of jihadists in the region.

Since 2012, jihadist and independence rebellions in the north have plunged Mali into a complex conflict that has left thousands of civilians and fighters dead, despite the intervention of UN, African and French forces.

Some of the groups fighting for independence signed a peace deal in 2015, but the Sahel country is still targeted by attacks from groups linked to al-Qaeda and the Islamic State.

The violence has also crossed the borders into neighbouring Burkina Faso and Niger.