Turkey's defence ministry said on Tuesday Kurdish YPG militia had killed three people and wounded eight in a missile attack on a school in the Tel Abyad region of northern Syria which they were meant to have withdrawn from under a ceasefire agreement.
The report came a day after Turkey threatened a new military operation in northeast Syria if the area was not cleared of the militia.
A Turkish incursion last month against the Syrian YPG dubbed Operation Peace Spring drew international condemnation. Ankara accuses the YPG, which spearheaded the U.S.-led war against Islamic State, of links with Kurdish PKK separatists in Turkey.
"The PKK/YPG who continued their harassments and attacks, and conducted bombings in the Operation Peace Spring area, have now targeted a school in Tel Abyad's Curn village," a Turkish defence ministry statement said.
Tel Abyad is one of two major border towns that saw the heaviest fighting when Ankara launched the incursion on Oct. 9.
"Three innocent civilians died and eight civilians, including children, were injured," the statement said.
Turkey halted its offensive after striking deals with Russia and the United States. While Moscow has said the YPG have withdrawn to at least 30 km (18 miles) from the border, Ankara has been sceptical and held out the possibility of new attacks if members of what it sees as a terrorist group remain.
Turkish Foreign Minister Mevlut Cavusoglu was quoted on Monday as saying his country would launch a new operation if the area was not cleared of YPG militia. Russia said any such move would damage efforts to stabilise the region.