BEIRUT: Thousands of Syrian civilians fled north toward the Turkish border on Thursday as Assad regime troops drove into the last remaining opposition-held territory in Idlib and adjacent provinces.

The ground offensive beneath an air bombardment by Russian warplanes has forced 150,000 people from their homes, raising concerns of a new humanitarian crisis in northwest Syria.

Rasheed Al-Ahmed, a pharmacist from the village of Kfar Nabudah, said all the village’s residents had fled north and settled in camps along the border with Turkey. 

Regime troops had poured into the village as aircraft flew overhead, and neighboring villages were also emptied by the rapid offensive.

“People are living between trees and in farms,” said Al-Ahmed, who found his family a safe place in Atmeh, near the border. “It is a deplorable situation.”

Regime forces captured the key town of Qalaat Al-Madiq, the entrance point into opposition territory for insurgents and civilians moved from territory captured by the army under previous surrender deals. 

The Britain-based Syrian Observatory for Human Rights war monitoring group said opposition forces had withdrawn there after being nearly encircled by regime troops.

The latest wave of fighting that began last week is the most serious challenge yet to a cease-fire in the region, brokered by Russia and Turkey in September. 

Turkey failed to deliver on the agreed withdrawal of extremist factions from the planned buffer zone and, in January, the Hayat Tahrir Al-Sham group, which is dominated by militants from Al-Qaeda’s former Syrian branch, took control of the region, prompting an increase in clashes.

Thursday’s push came a day after Syrian troops took the nearby village of Kfar Nabudah, which activists called Idlib’s first line of defense.

The regime appears to be trying to secure access to a major highway that cuts through the opposition-held enclave. The road was to reopen before the end of 2018, following the cease-fire agreement, but it remains closed.