Turkish drone strikes in Syria’s northwestern Idlib province killed 19 government soldiers on Sunday, a war monitor reported, as tensions soared between Damascus and Ankara.

The 19 died in strikes on a military convoy in the Jabal al-Zawiya area and a base near Maaret al-Numan city, the Syrian Observatory for Human Rights said.

The report came hours after Turkey shot down two Syrian warplanes, in an escalating offensive against the Damascus government in Idlib, where Islamist fighters backed by Ankara pose the biggest obstacle to Damascus seizing back control over all of Syria.

Following weeks of violence in the province, Turkey confirmed a full military operation against Russian-backed Syrian forces after 34 Turkish soldiers were killed last week in an airstrike blamed on Damascus.

However, Ankara has insisted it does not want to clash directly with Moscow.

“One anti-aircraft system that shot down one of our armed drones and two other anti-aircraft systems have been destroyed, and two SU-24 regime planes that were attacking our aircraft have been downed,” Turkey’s defence ministry said.

Syrian state media said Turkish forces “targeted” two of its planes over Idlib. A rebel group and the Syrian Observatory for Human Rights, a Britain-based war monitor, both said the planes had been downed.

The situation in Idlib was already volatile as the government supported by Russian air power pressed an assault on the region in a bid to retake the last opposition enclave in a nine-year civil war.

The confrontation between the Russia-backed Syrian forces and Nato-member Turkey, which supports Syrian rebels, has prompted worries over a wider conflict and a migrant crisis in Europe similar to 2015.

Migrant numbers have already surged along the rugged frontier after Turkish President Recep Tayyip Erdogan, seeking to pressure the EU over Syria, said the country had “opened the doors” to Europe.

Greece said on Sunday it has blocked nearly 10,000 migrants at its border with Turkey.

Turkish Defence Minister Hulusi Akar announced “operation ‘Spring Shield’” for the first time, adding that it “successfully continues”.

Turkish forces hit Syrian government positions after Erdogan warned Damascus would “pay a price” for the airstrike.

Under a 2018 deal with Russia meant to bring calm to Idlib, Turkey has 12 observation posts in Syria -- but several have come under fire from Syrian President Bashar al-Assad’s forces.

Turkey wants the international community to establish a no-fly zone over Idlib.

Sana Syrian state media reported that the government shot down a Turkish drone near the town of Saraqeb, publishing footage of an aircraft tumbling from the sky in flames. Those images could not be immediately confirmed.

But Turkish defence ministry confirmed one of its drones was shot down.