Turkish army shelling killed six members of the Kurdish security forces in an area of northwestern Syria controlled by Kurdish groups overnight, the Syrian Observatory for Human Rights reported.
The Afrin region of northwestern Syria is controlled by the Kurdish YPG militia which holds swathes of northern Syria.
Turkey last month launched an incursion into northern Syria in an area some 100 km (60 miles) east of Afrin to stop further expansion of YPG territory and to drive the jihadist group Islamic State from the border.
A statement issued by the Kurdish authorities in Afrin said the attack was a provocation by the Turkish army to “ignite the fire of war”. “We will carry out the appropriate response … if these type of attacks are repeated,” the statement said.
Turkey is concerned that further consolidation of Kurdish influence in northern Syria could fuel separatist sentiment among its own Kurdish minority. The Kurdistan Workers Party (PKK) has fought a three-decade insurgency for Kurdish autonomy in southeastern Turkey.
The YPG, viewed by Turkey as an extension of the PKK, has been a vital partner for the United States in the campaign it has been leading against Islamic State in Syria.