The Iraqi military says its forces have pushed deeper into a key Islamic State-held town north of Baghdad days after launching an operation to retake it.

The Joint Military Operation Command said the Iraqi flag was hoisted on Thursday over the mayor's office and the main hospital complex in the town of Shirqat. The statement added that Iraqi forces were pushing forward to the city center.

Backed by paramilitary troops, mostly Shiite militiamen, and aerial support from the U.S.-led international coalition, government forces launched the Shirqat operation on Tuesday. The town lies near the city of Mosul, which is the IS group's last major urban stronghold in Iraq.

Shirqat, about 155 miles (250 kilometers) northwest of Baghdad, was among the first areas to fall into IS hands during the militants' June 2014 blitz.