Turkey's president says the behaviour of US special forces in Syria is causing a rift in the fight against DAESH.
Syrian opposition forces do not want interference from US special forces, Turkish President Recep Tayyip Erdoğan said on Monday.
Erdoğan was referring to a small unit of US forces who entered the Syrian town of al-Rai on Friday as part of an operation to coordinate air strikes against the DAESH terrorist group.
Their presence in the town was met with protests by Syrian opposition groups, who forced five or six US military personnel to withdraw towards the Turkish border.
Ahrar al-Sharqiya, an opposition group within the Free Syrian Army (FSA) coalition, said in a written statement that they refuse to fight alongside US forces, accusing Washington of supporting "terrorists.
Despite enjoying a degree of support from the US, the FSA are at loggerheads with the US-backed Syrian Democratic Forces (SDF), which is mainly comprised of YPG members.
The YPG is the armed wing of the PYD, an extension of the PKK, which is recognised as a terrorist organisation by Turkey, the EU and the US.
The UK-based Syrian Observatory for Human Rights confirmed the incident, saying the US forces had left al-Rai but were still on Syrian soil.
Erdoğan blamed the "behaviour" of US officials for exacerbating tension with Syrian opposition groups. Turkey's stance has put it at odds with Washington, which sees the YPG as a reliable ally on the ground in Syria.
Turkish-backed Free Syrian Army (FSA) fighters have been battling against DAESH along the Turkish-Syrian border as part of Operation Euphrates Shield, which was launched last month.
FSA forces recently pushed the terrorists away from the frontier with the support of Turkish warplanes and tanks.
The Turkish president said the FSA may extend their zone of control in northern Syria by pushing south and are now focused on heading towards the DAESH-held town of Al-Bab
"Jarablus and al-Rai have been cleansed, now we are moving towards Al-Bab... We will go there and stop (DAESH) from being a threat to us," he said.
Erdoğan's remarks came during a news conference in Istanbul before departing for New York, where he is due to address the United Nations General Assembly.
At the UN meeting, Erdoğan is expected to discuss the crises in Syria and Iraq, the fight against terrorism and July's failed coup attempt in Turkey.