Iraqi and Kurdish forces on Thursday launched a major advance north and northeast of Mosul, Daesh's stronghold in Iraq, on the fourth day of a mission to recapture the city.
The General Command of Peshmerga Forces of Kurdistan Region said "a large-scale operation was launched by Peshmerga Forces from (the) north and north-east of Mosul as part of the ongoing campaign to clear ISIL (Daesh) terrorists from Ninewa province."
It added that the operation aimed "to tighten the noose around ISIL," using an acronym for the extremist group, and said it would strike on three fronts following on from gains made by Peshmerga and Iraq forces in the south.
Meanwhile, largely-Shia militias, known as Hashd al-Shaabi, arrived on the western front, a statement by the group said on Facebook.
Daesh captured Mosul and other large areas of Sunni-populated northern and western Iraq in a lightning offensive in mid-2014.
After a series of gains by security forces over the past 18 months, it is now the only major Iraqi city held by the jihadists.
Daesh still holds territory in neighbouring Syria, though there too it is on the back foot.