MOSUL, Iraq — Some 300 Islamic State fighters remain in the small patch of territory still controlled by the group in Mosul's Old City, a senior Iraqi commander said Wednesday.

Lt. Gen. Sami al-Aridi of Iraq's special forces told The Associated Press that the militants' hold on Mosul has shrunk to a 500 square meter (600 sq. yard) area. A large number of civilians are believed to be trapped in the ISIS-run enclave, with around 1,500 fleeing with every 100-meter advance by Iraqi forces.

mosul 7517-2

Smoke billows over the Old City after several strikes as Iraqi forces continue their advance against Islamic State militants in Mosul, Iraq, Monday, July 3, 2017.
Photo Credit: Felipe Dana/AP

Iraqi forces moved to besiege the Old City before launching their attack in order to prevent ISIS fighters from fleeing to neighboring Syria, but al-Aridi said hundreds of militants still managed to escape from the Old City alone.

"They just shave their beards and walk out," al-Aridi said. "Just yesterday we captured two among a group of women and children."

Late Tuesday, Iraq's Prime Minister Haider al-Abadi congratulated the armed forces on a "big victory" in Mosul, despite ongoing clashes. The prime minister declared an end to the extremist group's self-styled Islamic caliphate in June.

ISIS captured Mosul in a matter of days when it swept across northern and central Iraq in the summer of 2014. Iraqi forces backed by a U.S.-led coalition launched a major operation to retake the city in October.

n Iraqi Special Forces soldiers watches for Islamic State militants as they continue their advance in the Old City of Mosul, Iraq, Monday, July 3, 2017.

Photo Credit: Felipe Dana/AP