A source in Ahrar al-Sham also said Tahrir al-Sham had surrounded the crossing, but vowed not to give it up.

War monitors reported that Tahrir al-Sham attacked military positions of Ahrar al-Sham on Tuesday, in the heaviest fighting between the two sides which have long vied for control in Idlib.

In clashes early this year, several more hardline Islamist groups joined Tahrir al-Sham, which is headed by al Qaeda‘s former Syria branch, previously known as the Nusra Front.