Turkey said on Tuesday 51 Syrian soldiers were killed in northwest Syria as Turkish-backed rebels struck back against Russian-supported government forces who had made gains in their campaign to eliminate the last insurgent bastion in the country.
The Turkish Defence Ministry cited sources on the ground for the information, adding that two Syrian tanks and one ammunition store were destroyed as well.
Hours before, a war monitor reported that Syrian government forces seized control of the main Aleppo-to-Damascus highway running through the embattled northwest province of Idlib for the first time since the early days of the civil war in 2012.
But Syrian state media made no mention of this and rebel sources later said fighting was continuing in some northern areas near the M-5 highway, which links Aleppo with the capital Damascus and ultimately Deraa in the far south.
In response, insurgents shot down a Syrian military helicopter and advanced toward the town of Nairab, which the Turkish Defence Ministry said had been abandoned by Syrian government forces.
A Turkish official said the rebels, bolstered by Turkish artillery, had begun "a full-fledged attack" on an area recently lost to the government side near Saraqeb, a strategic crossroads town on the M5 highway. A rebel commander told Reuters they were pushing back government forces there.
For its part, the Syrian army said on Tuesday it would respond to attacks by Turkish forces who it said were trying to halt army advances into Idlib province.
The flare-up of fighting has given rise to some of the most serious confrontations between Ankara and Damascus in the nine-year-old war in which Russia and Iran have backed Syrian President Bashar al-Assad.