Turkish broadcaster NTV made the announcement on Monday, citing local sources.
Turkey’s Prime Minister Binali Yildirim was also reported by NTV as saying that Turkish military forces had begun carrying out duties in Manbij.
Later in the day, the Turkish military confirmed the media report and said Turkish and US soldiers had begun patrols in northern Syria along the line between the city of Manbij and a neighboring region under Ankara’s control, Presstv Reported.
The military added in a statement on Twitter that the patrols were being conducted independent of each other along the line between Manbij and the area of which Turkey seized control in its "Euphrates Shield" operation in northern Syria in August 2016 to stop the advance of Kurdish militia forces.
Manbij has been a source of tension between the two NATO allies for months.
Earlier this month, Ankara and Washington agreed on a plan for the withdrawal of Kurdish militants from the northern Syrian city, and the deployment of Turkish and US soldiers in the region to stabilize the area.
Ties between Ankara and Washington have further soured over the latter’s support for Kurdish militants of the People’s Protection Units (YPG) operating at the Turkish doorstep.
Turkey regards the YPG as a terrorist group and an affiliate of the outlawed Kurdistan Workers’ Party (PKK), but the US considers the Kurdish group an ally in Syria.
The US had angered Turkey by announcing a plan for the formation of a Kurdish militant force in Syria near the Turkish border, prompting Ankara in January to launch a military operation against the US-backed militants.
Earlier this year, Turkey seized the Syrian region of Afrin and threatened to expand its offensive to Manbij.
Ankara has repeatedly accused Washington of failing to fulfill its promise regarding the withdrawal of its allied militants from Manbij after the purge of the Daesh terrorist group in August 2016.