Patrols were reduced following the Turkish strikes that began on November 20 in Kurdish-controlled areas of Syria and Iraq, in response to a deadly Istanbul bombing that Ankara blamed on Kurdish groups.

The Kurds denied responsibility.

Hundreds of American troops are in Syria as part of the fight against remnants of the Islamic State group jihadists.

Two four-vehicle patrols bearing US flags set off separately from a base in Rmeilan in Hasakeh province, the AFP correspondent said.

A vehicle belonging to the Kurdish-led Syrian Democratic Forces (SDF) accompanied each convoy, which travelled in different directions towards Syria's borders.

"The international coalition in cooperation with the Syrian Democratic Forces resumed its usual patrols in northeast Syria following a reduction due to Turkish strikes in the area," a Kurdish military source told AFP.

The source requested anonymity as he was not authorised to speak on the matter.

The usual 20 weekly patrols had dropped to around five or six following the Turkish strikes, which Ankara said it carried out with aircraft and drones.

The US supports the SDF, which is the Kurds' de facto army in the area and led the battle that dislodged IS from the last scraps of their Syrian territory in 2019.

Turkey said it struck targets of the Syrian Kurdish People's Protection Units (YPG), which dominate the SDF but which Ankara sees as an offshoot of the Kurdistan Workers' Party (PKK).

Turkey and its Western allies designate the PKK as a terrorist group.

The SDF "needs to focus on repelling the Turkish threats and protecting its areas", the Kurdish military source said.

The Syrian Observatory for Human Rights, a Britain-based war monitor with a vast network of sources on the ground, said patrols were also seen Friday in Deir Ezzor province further south.

Turkey has also threatened a ground operation in the semi-autonomous Syrian Kurdish zones, something which US Defence Secretary Lloyd Austin on Wednesday expressed "strong opposition" to.

The SDF has warned that a Turkish incursion would jeopardise the fight against IS.