U.S. army vehicles drive north of Manbij city
© Rodi Said / Reuters
US-led coalition forces in Syria have returned fire after being shot at by Turkey-backed rebels near the northern city of Manbij, according to a coalition spokesman.

"Our forces did receive fire and return fire and then moved to a secure location," coalition spokesman Colonel Ryan Dillon told Reuters by phone.

He added that the coalition has asked Turkey to tell the rebels it supports in the area that firing on US-led coalition forces "is not acceptable."

US ground forces are in northern Syria as part of the coalition's efforts to support the Syrian Democratic Forces (SDF), a local alliance of Kurdish and Arab militias battling Islamic State (IS, formerly ISIS/ISIL).

"Our overt patrols that have been conducting patrols in that area to keep tensions down received fire multiple times over the course of the last two weeks," Dillon said.

"We let our counterparts in Turkey know this and we continue to conduct these patrols but are always prepared and ready to defend ourselves in that area."

The US-led coalition, consisting of more than 60 states, began conducting airstrikes against IS in Syria and Iraq in 2014, despite not having authorization from either the Syrian government or the UN Security Council.

The coalition is not supporting four de-escalation zones which were agreed upon at talks in Astana, Kazakhstan, in May. The proposal was, however, signed by Russia, Iran, and Turkey, with the approval of the Syrian government. The UN has welcomed the initiative.