Lt. Gen. Raid Shakir Jaudat said the militants were increasingly cut off from each other and that their leaders were fleeing the remaining pockets of militant control.
"The terrorist organization Daesh (is) living in a state of shock, confusion and defeat, and its fighters are fighting in isolated groups," Jaudat said, using an Arabic acronym for ISIS.
"Our field intelligence units indicate that the terrorist organization is falling apart, and its leadership (is) running away from Mosul."
Iraqi forces retook the eastern part of Mosul from ISIS a month ago, completing a key phase in the effort to retake Iraq's second-largest city from the terror group. Jaudat said government artillery was targeting remaining "terrorist dens" in the western half of the city.
He said his forces were combing the al-Ghazalani, al-Jawasq and al-Tayaran neighborhoods in search of fighters, improvised explosive devices and booby traps.
ISIS meeting bombarded
As the battle to seize western Mosul rages on, Iraqi militants and government troops pounded an ISIS meeting about 70 kilometers (43 miles) away, killing and injuring dozens, said the media office for the Popular Mobilization Unit, or PMU.
The PMU is an umbrella group of militant organizations working with government forces to free ISIS-held areas of Nineveh province, including Mosul, the provincial capital.
Two artillery strikes, planned in conjunction with an Iraqi army brigade, killed or injured more than 70 gathered ISIS fighters, the PMU media office said.
But the fight against ISIS has taken a humanitarian toll.
About 14,000 people have fled western Mosul since Iraqi forces started their operation there February 19, said Jassem Mohammad al-Jaff, Iraq's minister of displacement and migration.
The UN Office for the Coordination of Humanitarian Affairs said food and water have been distributed to those fleeing ISIS-held areas.
But the UN office said civilians in many neighborhoods of southern and western Mosul have no access to drinking water.
It added that as many as 75 civilians have been treated as trauma casualties since the campaign began.
But the number of internally displaced people inside Iraq has been reduced to 2.7 million from 4.3 million, Jaff said.
He said 1.6 million people have returned to their towns, cities and villages.
Key bridge retaken
On Monday, the army reported it has recaptured a bridge across the Tigris River in west Mosul, where fierce battles are ongoing to oust ISIS.
While all five bridges linking the government-held eastern Mosul to the western part have been destroyed, the takeover of the fourth bridge will allow Iraqi forces to lay a ramp over the broken part and open a supply route from the east.
The battle to take back west Mosul, where about 750,000 people are believed to be living, has proved to be challenging. The narrow, densely populated streets there make the impact of heavy weaponry deadly and indiscriminate, and access to aid difficult.