The Turkey-backed Free Syrian Army (FSA) on Wednesday captured the villages of Tel Torin and Qarah Sharq, located 22 kilometres west of the northern Syrian town of Manbij, from the YPG-dominated Syrian Democratic Forces (SDF), a spokesman for the militia said.
There was no immediate comment from Turkey, which is waging its Operation Euphrates Shield military campaign with FSA forces.
Euphrates Shield was launched on August 24, 2016, with the aim of ridding Turkey's southern border of the presence of Daesh and the YPG, a Syrian-offshoot of the PKK, which the US and Ankara designate as a terrorist group.
Turkish President Recep Tayyip Erdogan said on Tuesday that Manbij was the next target of the campaign following the capture of al-Bab from Daesh last week.
The new offensive is focused on a string of villages controlled by the Manbij Military Council, part of the US-backed SDF alliance.
Meanwhile, talks between the United States and Turkey are underway for a long-anticipated operation to take back the Syrian city of Raqqa from Daesh.
The top US general in charge of fighting Daesh, Stephen Townsend, also confirmed that some Kurdish armed groups in Syria would be part of an offensive.
That has given Turkey cause for concern, because it considers the YPG a branch of the PKK terror organisation.
Meanwhile, Russian and Syrian regime aircraft bombed positions held by the US-backed Syrian Arab Coalition near the Syrian town of al-Bab on Tuesday, inflicting casualties, US Army Lieutenant General Stephen Townsend said on Wednesday.
"Yesterday, we had some Russian aircraft and [Syrian] regime aircraft bomb some villages that I believe they thought were held by Daesh, yet they were actually - on the ground - were some of our Syrian Arab coalition forces," Townsend told a Pentagon news briefing.
Russian-backed Syrian regime forces and their allies recaptured the historic Palmyra citadel, on the city's western outskirts, from Daesh fighters on Wednesday, a military media unit run by Hezbollah said.
Daesh had captured Palmyra, whose ancient ruins are a UNESCO World Heritage Site, twice during Syria's six-year-old conflict.
Syrian regime forces and its allies, backed by Russian air support, recaptured the city from Daesh in March last year, but the militant group seized it again in December.
Daesh has razed ancient monuments during both of its spells in control of Palmyra - destruction the United Nations has condemned as a war crime.
The Syrian Observatory for Human Rights, a Britain-based organisation that reports on the war, said regime forces are expected to storm Palmyra at "any moment."
Russia has said its aircraft are supporting the army offensive in Palmyra.