The Iraqi militias, partially trained by the Iranian military, will attempt to complete the encirclement of Mosul, blocking it from the West, a representative said.
Daesh has exploited civilians living to the west of Mosul, creating human shields consisting of women and children from local settlements. Some 8,000 families have been abused this way, the UN reported on Friday.
"This is the most important and dangerous line because it connects Mosul to Raqqa and is the only supply line for Daesh," Ahmed al-Asadi, a spokesperson for the Popular Mobilization Units, told Iraqi TV on Friday, stressing that use of the western avenue is essential to defeat Daesh.
Asadi added that the offensive is due to begin in "a few days or hours," adding the first target will be Tal Afar, a town 35 miles west of Mosul, currently occupied by Daesh.
"Tal Afar is the final destination… it is the pyramid’s peak,” he asserted. “But there are villages on the way that need to be liberated before reaching Tal Afar."
The participation of Shia forces in the Mosul battle has long been under scrutiny, with players including the US and Turkey strongly opposing their participation as a move to bolster Iran, the major Shia country in the world.
Rights watchdog organizations cautioned Baghdad that, upon retaking territories from Daesh, Shia militias could carry out acts of revenge on the Sunni population, increasing violence.
In the course of operations Iraqi forces liberated one small town and 12 villages located to the east and northeast of the city. Daesh has suffered harsh losses, as many “flee or blow themselves up in trucks rigged with explosives," according to Iraqi General Mukamed Masid.
On Friday, forces reported a halt in the offensive, some six to 12 miles from Mosul, to ensure rear areas were cleared of the jihadists. At the same time, US-led airstrikes have continued.
Mosul was seized by Daesh in 2014, and was declared one of two capitals of a self-declared caliphate, by the organization’s then-leader Abu Bakr al-Baghdadi.