The Turkish army struck positions of Kurdish fighters inside Syria for a second day Sunday, claiming it was in response to incoming fire, the state-run Anatolia news agency reported.
The army hit targets of the Democratic Union Party (PYD) around the Syrian town of Azaz using howitzers stationed on the Turkish side of the border, the report said.
Turkish forces had already carried out a similar bombardment on Saturday.
Anatolia gave no further details but military sources quoted by Turkish media said the new exchange took place from 0700 GMT on Sunday.
Turkish forces would continue to strike PYD targets in Syria as long as the army came under fire from their positions, the military sources added.
Turkish media reports said the fire was clearly audible from the border crossing close to the southern Turkish town of Kilis.
NTV television said that Turkish forces had also captured three suspected PYD members in Kilis, without giving further details.
Turkey has been gravely alarmed by the push by the PYD and their People's Protection Units (YPG) militia westwards along the Syrian border to the flashpoint town of Azaz.
Ankara accuses the PYD of being the Syrian branch of the Kurdistan Workers Party (PKK) which has waged a decades-long insurgency against the Turkish state that intensified in the last months.
But Washington has been relying on the YPG as one of its few effective allies on the ground in the fight against Islamic State (IS) jihadists in northern Syria.
The PKK is recognized by the United States as a terror group but not the YPG or PYD.
The issue is causing increasing friction between the two NATO allies and complicating efforts to find a solution to Syria's almost five year civil war.
US State Department spokesman John Kirby said in a statement late Saturday that Washington urged Turkey to cease its cross-border artillery fire.
He said the United States had also urged the Kurdish fighters "not to take advantage of a confused situation by seizing new territory."
AFP contributed to this report.