Artillery shelling by Syrian government forces pounded parts of the northwestern Idlib province on Saturday, following victories by al-Qaida-linked operatives against Turkey-backed opposition fighters, Syria's state news agency reported.
The violence came as officials in neighboring Turkey said efforts are being exerted to maintain stability in Idlib.
SANA said the shelling focused on the areas of Zarzour near the border with Turkey and Tamanaa near Maaret al-Numan, which al-Qaida-linked militants captured this week from Turkey-backed opposition fighters. SANA reported casualties among the al-Qaida-linked operatives.
The Britain-based Syrian Observatory for Human Rights said the government shelled six areas in and near Idlib province.
Also over the weekend, Turkish troops and tanks carried out military exercises on the border with Syria, state-run media reported.
On Friday, a Turkish security source said the Turkish army had been rotating forces in and out of the Idlib, the last major rebel-held area in Syria, and declined to say whether the latest movement was in preparation for an operation inside Syria itself.
The Syrian Observatory for Human Rights, a U.K.-based monitoring group, said a Turkish convoy had entered Syria.
Islamist fighters have tightened their control over the Idlib region following more than a week of fighting with Turkey-backed Syrian rebels.
The rise of the jihadist Hayat Tahrir al Sham has raised doubt over the future of a deal agreed in September between Turkey – which has several military observation posts in Idlib – and Syrian President Bashar Assad's main ally Russia to avert a Syrian government army assault. The agreement requires banned Islamist groups to be expelled from a frontline buffer zone.
The escalation in Idlib comes as U.S. forces prepare to withdraw from a separate region of northern and eastern Syria.
Earlier on Saturday, the Turkish defense minister, chief of general staff and the intelligence agency head visited border military units and discussed "measures to establish peace and stability in the region," the ministry said in a statement.
"We are making every effort to preserve the ceasefire and stability in Idlib, in line with the Sochi agreement. Our close cooperation with Russia continues," Defense Minister Hulusi Akar said.
Akar's comments came a day after Russia said it remained committed to the agreement it had struck with Turkey to stabilize a de-escalation zone in Idlib, but said Moscow was worried by an increase in the number of ceasefire violations.
