The crossing, known as Jousieh on the Syrian side, became a key escape route for those fleeing the Israel-Hezbollah war after the main border crossing between the two countries was hit.

But it was put out of service late last month when an Israeli strike created a large crater that blocked vehicle traffic.

"A new Israeli air strike hit the border post of Jousieh, where many Lebanese and Syrians cross from Lebanon to Syria," Grandi said on social media platform X.

"Humanitarian structures were also struck," he said, adding that "even fleeing and taking care of those who flee are becoming difficult and dangerous as the war continues to spread."

The Syrian Observatory for Human Rights, a Britain-based war monitor, said two Israeli strikes hit the Jousieh crossing on Saturday.

The raid came after the main crossing between Beirut and Damascus, known as Masnaa on the Lebanese side, was forced to close by an Israel strike on October 4.

There are six official crossings between Lebanon and Syria, although there are many unofficial routes across the porous border.

Israel has repeatedly accused Hezbollah of transporting weapons to Lebanon from Syria through the crossings.