Syrian regime troops seized the northwestern crossroads town of Saraqeb on Saturday, which is the second key highway town to be captured by regime forces in the past two weeks.
Saraqeb connects the capital to Aleppo, running up from the Jordanian border in the south. It is Syria's longest highway.
"Army units now exercise full control over Saraqeb," state television reported, saying the regime forces were combing the area for landmines and explosives.
Last month, regime forces took full control of opposition-held Maarat al-Numan, 33 km (20 miles) south of Idlib city.
Weeks of intensive airstrikes and a bruising ground offensive have emptied entire towns in the Idlib region and sent hundreds of thousands fleeing, AFP reported.
The clash has displaced 586,000 people since December, according to the United Nations.
Meanwhile, the Syrian Observatory for Human Rights said more than 300 civilians were also killed.
After a string of advances since the intervention of Russia on its side in 2015, the Syrian regime now controls more than 70 percent of Syrian territory.
