U.N. fears for 10,000 families trapped in ISIS-held Falluja as Iraq army advances

The United Nations says it fears for the safety of an estimated 10,000 families trapped in Falluja as Iraqi forces press in to retake the city from ISIS.

Fierce fighting has been raging around Falluja since Iraq's military launched an offensive Monday to reclaim the traditionally Sunni-dominated city, about 65 kilometers (40 miles) west of Baghdad, from the terror group.

And with tens of thousands of residents unable to flee the clutches of ISIS, the U.N. fears that civilians will pay a heavy toll for the liberation of the city.

Iraq's air force has airdropped thousands of leaflets on Falluja instructing residents to leave and promising them passage through "safe corridors" established by the military to camps outside the city.

The government has set up a hotline for residents to call or text if they require evacuation, while state television has broadcast advisories to residents to wave white flags over their homes if they can't flee, and to stay away from ISIS facilities and gatherings.

But activists say ISIS has been preventing residents from leaving, and has cut many communication lines — leaving thousands potentially caught in the crossfire between government troops, backed by Shiite militia and tribal fighters, and the Sunni terror group.

An estimated 10,000 families remain trapped in the city "in a very precarious situation," the U.N. said in a statement.

The push on Falluja comes as an alliance of U.S.-backed Kurdish and Arab forces announced Tuesday that an offensive was underway to retake areas to the north of the de facto ISIS capital of Raqqa, in neighboring Syria.