World Bulletin / News Desk
Police Brigadier Mazhar Abdel-Basit said four tons of materials used to manufacture explosives had been found in the depot.
Since late October, Iraqi forces, backed by U.S.-led coalition warplanes, have been trying to recapture Mosul, which ISIL overran in mid-2014.
Last week, the Iraqi army announced the "total liberation" of eastern Mosul -- after nearly three months of fighting -- from the grip of the extremist group.
ISIL militants are now reportedly shoring up their defenses in western Mosul in anticipation of large-scale army operations to recapture the area.
"For the last three days, the militants have been setting up barricades in western Mosul near the Tigris River," Salam al-Draji, a local police officer, told Anadolu Agency.
The reinforcements, he said, were meant to prevent Iraqi forces from advancing into ISIL-held districts of the war-battered city.