Nearly 50 soldiers and rebels have been killed in clashes near Syria's northern border, as Turkey hit back against what it said was new mortar fire from inside Syria.
Damascus, for its part, said four Turks were among a convoy of "terrorists" killed in the heart of Aleppo, just hours after UN condemnation of deadly jihadist bombings in the country's commercial capital.
Forty government soldiers and nine rebels were killed on Saturday when rebels took a town in the northwestern province of Idlib near the border, the Syrian Observatory for Human Rights said.
"The clashes at Khirbat al-Joz ... ended when fighters of the rebel brigades took control of the area," said the Britain-based watchdog.
"The fighting lasted more than 12 hours and resulted in at least 40 dead among the regular forces, including five officers, and nine (rebel) fighters," it added after earlier reporting 25 soldiers and three rebels dead.
Turkish officials said they were sure a mortar round that struck on Saturday morning was fired by pro-government forces in Syria, and not rebels who have been fighting for nearly 19 months to oust President Bashar al-Assad.
It prompted fresh retaliatory fire after reprisals on Wednesday and Thursday for the previous shelling, the Hatay provincial governor's office said.
"A mortar round struck today (Saturday) at 7.00am (1500 AEST) about 50 metres inside Turkish territory in an open space about 700 metres from the village of Guvecci and about 300 metres from a police station."
No casualties were reported.
The Turkish army responded with four mortar rounds, the governor's office said, adding that the Syrian fire had come from loyalists who were firing at rebels near the border.
The cross-border exchanges came despite unanimous condemnation from the UN Security Council on Thursday of deadly shelling from the Syrian side further east in Sanliurfa province that killed five people.
Following that incident, the Turkish parliament authorised further military action but Prime Minister Recep Tayyip Erdogan said he was not seeking a mandate for war.
In a new statement on Friday, the Security Council condemned bombings on Wednesday claimed by a jihadist group that killed nearly 50 people in Aleppo, expressing condolences to families of the victims "of these heinous acts."
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