Maj. Gen. Sami al-Aridi said heavy fighting broke out near the media station, the only state TV building in the province, as his troops tried to push into the city's more urban areas, AP reported.
Special forces entered the eastern outskirts of the city earlier Tuesday, marking the first time Iraqi troops have entered.
The recapture of Mosul would mark the Takfiri militants’ effective defeat in the Iraqi half of the territory they had seized.
Mosul is still home to 1.5 million residents, making it four of five times bigger than any other city they controlled in both Iraq and Syria.
Hadi al-Amiri, leader of the Badr Organization, warned Sunday that “the battle of Mosul will not be a picnic” and could last months.
“We are afraid that Mosul would be another Aleppo, but we hope that will not happen,” Amiri told reporters in Zarqa, south of Mosul.
Iraqi security forces and Peshmerga fighters started a massive offensive against the Takfiri group on Oct. 17.