"All Daesh (IS) fighters have left. There is no resistance," Sabah al-Numan told AFP, adding that the entire perimeter had to be cleared of mines and booby traps before troops could move in.
"Our forces have surrounded the government complex. They are checking all entrances and surrounding buildings before moving in," he said.
"The operation is almost wrapped up. Our forces will enter in the coming hours," Numan said.
Iraqi forces backed by US-led coalition air strikes had punched into the city centre on Tuesday, in a final push to retake the city they lost in May.