Islamic State fighters attacked the town of Tel Abyad controlled by the Syrian Kurdish YPG militia at the Turkish border as well as the nearby town of Suluk on Saturday (February 27), YPG spokesman Redur Xelil told Reuters.
The YPG captured Tel Abyad from IS last year in an offensive backed by U.S.-led air strikes.
Kanal Urfa channel showed pictures of plumes of smoke rising from Tel Abyad, visible from Turkey's border town of Akcakale.
YPG spokesman said some of the attackers on Saturday infiltrated from the Turkish border to the north, reiterating accusations that Turkey was supporting the group.
Turkey has consistently denied those accusations.
Other attackers infiltrated from the south, he said.