Security forces and civilian fighters still hold parts of Tal Afar, in Nineveh province, along a strategic corridor to Syria, according to deputy provincial council chief Nuriddin Qabalan.
Qabalan said militants controlled most of Tal Afar and the surrounding area, adding there were pockets of resistance, and that soldiers, policemen and residents held on to parts of the airport.
Fifty civilians were killed in the violence, along with dozens of militants and members of the security forces, he said.
Militants in the past week took control of the vast majority of Nineveh province as part of a swift offensive that saw them seize provincial capital Mosul as well as parts of three other provinces.