U.S.-backed Iraqi government troops on Sunday fully liberated the sprawling complex of Mosul University, an Iraqi military spokesman said, a major step in the massive operation to retake the Islamic State group-held city of Mosul.

The spokesman for the Joint Military Command, Brig. Gen. Yahya Rasool, declared the campus was under the full control of Iraqi special forces, officially known as the Counter Terrorism Service, who raised the Iraqi flag over its buildings.

The troops searched campus buildings and removed bombs left by IS militants, Brig. Gen. Haider Fadhil of the special forces said. Fadhil added that the troops also entered the nearby Andalus neighborhood, which he expected would be fully retaken later in the day.

Iraqi forces had entered the university grounds Friday and managed to secure more than half of the campus the next day amid tough resistance from IS militants, who mainly deployed sniper and mortar fire to slow down the advancing troops.

Sunday's progress is the latest in a string of swift territorial gains in recent weeks by the U.S.-backed Iraqi military. Some 30,000 troops — a force that includes not only Iraq's conventional army but an array of other armed groups, including Shiite and Sunni paramilitary troops and Kurdish fighters — are taking part in the Mosul offensive which begun October 17.

The Islamic State group captured Mosul in 2014 along with nearly a third of Iraqi territory and large parts of neighboring Syria. Iraq's second-largest city, Mosul is the last major ISIS urban bastion in the country.