Surrounded and attacked, many IS commanders fled Mosul.

A US general said they discovered ISIS leaders fleeing Mosul after Iraqi forces launched a large-scale operation to retake the city.

Liberation forces attack a village on the outskirts of Mosul. Photo: AFP

"We informed the ISIS militants that their leader was abandoning them. We saw many Islamic State (ISIS) commanders moving out of Mosul," AFP quoted Major General Gary Volesky, commander of US forces in Iraq, as saying on October 19.

General Volesky declined to provide further information on the number of fleeing IS commanders and their destination, while asserting that the coalition had launched airstrikes targeting groups of fighters leaving Mosul.

Volesky predicted that the remaining IS militants in Mosul would consolidate into a larger group, as they had nowhere else to go.

Iraqi security forces are closely monitoring and checking Mosul residents leaving the city to prevent militants from blending in with civilians to escape.

On October 17, Iraqi Prime Minister Haider al-Abadi launched a major offensive to liberate the strategic city of Mosul from ISIS control.

The fighting is expected to last several weeks or months. The liberation forces number 30,000, comprising Iraqi troops, Kurdish Peshmerga militias, and Sunni militias.

US military officials estimate there are 3,500-5,000 ISIS fighters in Mosul, considered the last ISIS stronghold in Iraq. ISIS has lost significant ground over the past two years, having been pushed back from the cities of Tikrit, Ramadi, and Fallujah.

According to VNE