QABR AL-ABD, Iraq — Under the cover of dust and fog, Islamic State group fighters launched a series of counterattacks on Iraqi positions to the south and west of the militant-held city of Mosul late Friday night and into Saturday morning, according to Iraqi military commanders and officials.

The massive operation to retake Mosul was officially launched on Oct. 17, but after initially swift battlefield successes, the progress of Iraqi forces later slowed down in the face of fierce ISIS counterattacks and concerns over the safety of civilians still inside the city.

ISIS has largely failed to push back Iraqi troops, but its counterattacks have inflicted high casualties on both civilians and security forces alike and, in some cases, shaken morale.

The U.N. reported this week that nearly 2,000 members of the Iraqi forces were killed last month, but after coming under fire from the media arm of the Iraqi military, it announced Saturday it would discontinue publishing casualty figures for Iraq’s security forces.

West of Mosul, one Iraqi official said ISIS militants breached the defenses of Shiite militiamen at a village outside the northern Iraqi town of Tal Afar, which is west of Mosul.