U.S.-backed forces in Syria have breached the wall surrounding the Old City of Raqqa as they try to retake the city from the Islamic State extremist group, the U.S. Central Command said late on July 3.

"Coalition forces supported the [Syrian Democratic Forces] advance into the most heavily fortified portion of Raqqa by opening two small gaps in the Rafiqah Wall that surrounds the Old City," Centcom said.

Centcom said the SDF faced heavy resistance at the wall from IS fighters who used it as a combat position and planted mines and improvised explosive devices against advancing forces.

"Conducting targeted strikes on two small portions of the wall allowed coalition and partner forces to breach the Old City at locations of their choosing, denied ISIS the ability to use pre-positioned mines...protected SDF and civilian lives, and preserved the integrity of the greatest portion of the wall," the U.S. statement said.

"The portions targeted were 25-meter sections and will help preserve the remainder of the overall 2,500-meter wall," it added.

Based on reporting by AFP and Reuters