Kurdish-led fighters marching against IS near Syria's Raqqa

This frame grab from video provided on Monday, Nov. 7, 2016, by the Hawar News Agency, shows U.S.-backed fighters take position during fighting with the Islamic State group in the village of Laqtah, north of Raqqa, Syria. Turkey said Tuesday that Washington has promised that U.S.-backed Syrian Kurdish forces will only be involved in encircling the Islamic State stronghold of Raqqa and will not enter the city itself. (Hawar News Agency, via AP) (The Associated Press)

This frame grab from a video provided by Qasioun a Syrian opposition media outlet, shows U.S.-backed Syrian Democratic Forces fighters stationed near Ein Issa, north of Raqqa, Syria. Backed by U.S. airstrikes, Kurdish-led Syrian fighters clashed on Monday with Islamic State militants north of the city of Raqqa in Syria as they pushed ahead in their offensive aiming to liberate the city that has been the de facto capital of the extremist group since 2014. (Qasioun a Syrian Opposition Media Outlet, via AP) (The Associated Press)

A spokeswoman for a Kurdish-led force fighting the Islamic State group in northern Syria says they are the verge of surrounding a wide area north of the IS stronghold of Raqqa.

Cihan Ehmed of the U.S.-backed Syria Democratic Forces told The Associated Press Thursday that their fighters are pushing on two fronts north of Raqqa, the de facto capital of IS' self-declared caliphate.

She said once the forces coming from the two directions meet, they will surround 550 square kilometers (212 square miles) of territory controlled by the extremists.

The Britain-based Syrian Observatory for Human Rights said many people are fleeing areas north of Raqqa because of the fighting.

The SDF says they have committed 30,000 fighters to the offensive, aiming to eventually take Raqqa.