Syria activists and an opposition fighter say shelling and brief clashes have erupted along Turkey's border with northwestern Syria between Turkish forces and al-Qaida-linked militants.

Syrian opposition fighter Mustafa Sejari says Turkish artillery responded to a missile launched by al-Qaida-linked fighters across the border. Turkey's private Dogan news agency reported that Turkey fired seven howitzer rounds into Idlib on Sunday.

The Britain-based Syrian Observatory for Human Rights says Turkish shells fell near a displaced people's camp along the border, causing a panic but no casualties. The Observatory says the shelling was followed by brief clashes as tension continued.

Turkey's president announced Saturday his country has launched a "serious" operation in Syria's northwestern Idlib province with Turkey-backed Syrian opposition forces, following international efforts for de-escalation in the war-torn country.