Iranian-backed Shia militia groups in Iraq say they have launched an offensive against ISIL strongholds west of Mosul.
The Popular Mobilisation Forces are heading north towards Tal Afar, a town with a Shia majority before the self-proclaimed Islamic State overran it in 2014.
Lying near Turkey, the area has a sizeable Turkmen population and the operation could raise concern in Ankara.
The forces leading the assaults to retake Mosul hope to cut off the route to Syria by besieging the city from all sides.
Some 40km to the south, Iraqi Armed forces and police claim to have retaken the town of Al Shura, a main defensive point for ISIL.
A number of jihadist fighters were reportedly arrested or killed in the offensive.