Six women, one of whom was pregnant, were killed in a landmine blast in southern Mali on Friday, officials said, in the latest violence to hit the war-torn Sahel state.

The women were travelling in an ambulance in the southern Sikasso region, which rode over a mine, regional public prosecutor Dramane Diarra said.

The ambulance driver was the sole survivor of the explosion, but was "seriously wounded".

A local elected official, who declined to be named, told AFP that the driver had been taken to hospital. 

Photos of the destroyed ambulance -- which AFP was unable to independently verify -- circulated on social media on Friday.

Violence in the southern region where the blast occurred, near the border with Burkina Faso, has steadily increased in recent years.

Mali has been struggling to quell an Islamist insurgency that first broke out in the north in 2012, before spreading to the centre of the country and neighbouring Burkina Faso and Niger. 

Thousands of soldiers and civilians have died in the conflict to date, and hundreds of thousands have had to flee their homes.