US officials have expressed concerns over clashes in areas without Islamic State forces
Turkey's president has said his country will press ahead with its military operation in Syria, despite the US expressing "deep concern".
Recep Tayyip Erdogan vowed the offensive would continue until the Islamic State group and the Kurdish Syrian fighters no longer posed a threat to Turkey.
Turkey began its cross-border offensive late last week, with its tanks, artillery and warplanes backing Syrian rebels as they captured the town of Jarablus from Islamic State.
A monitoring group said 41 people were killed by Turkish airstrikes on Sunday, but Turkey denied any civilian casualties.
Mr Erdogan said today: "The Jarablus operation was a reflection of our determination.
"Our operations will continue until terror organisations such as Daesh (Islamic State), the PKK and its Syrian arm, the YPG, cease to be threats for our citizens."
When the campaign was launched, Turkey's leaders said the aim was to target terrorists of Islamic State and the Kurdish-dominated militia.
With Kurdish fighters quickly capturing land along Syria's border with Turkey, however, the Turkish incursion was also to prevent any further Kurdish gains.
Turkey sees the Kurdish YPG militia as an extension of the illegal Kurdistan Workers' Party (PKK).
Along with the US, Turkey is an important member of NATO but the Kurdish fighters it is attacking are a major part of the US fight against IS, which is led by the Syrian Democratic Forces (SDF).
The US, concerned that the focus of battle has shifted away from Islamic State, has objected to the fighting between Turkey and some opposition groups in northern Syria.
Brett McGurk, special presidential envoy for the coalition to counter IS, said: "We want to make clear that we find these clashes - in areas where ISIL (IS) is not located - unacceptable and a source of deep concern."
Quoting a briefing by the Department of Defense, he added: "We call on all armed actors to stand down...the US is actively engaged to facilitate such deconfliction and unity of focus on ISIL, which remains a lethal and common threat."