BEIRUT: A rebel coalition led by Al-Qaeda's Syria affiliate Thursday seized Ariha, the last remaining government-held city in the northwestern province of Idlib, activists said.

The Syrian Observatory for Human Rights said the Nusra Front and its allies captured the city after fierce clashes with pro-government forces, including Hezbollah fighters, who were then seen pulling out.

"Jaish al-Fatah has taken full control of the city of Ariha after a lightning offensive that ended with a heavy pullout of regime forces and their allies Hezbollah from the western side of the city," Observatory head Rami Abdel Rahman told AFP.

Jaish al-Fatah, or Army of Conquest, is the name of the coalition which comprises the Nusra Front and its allies - mostly Islamist rebel groups.

The Britain-based monitor said dozens of Syrian military vehicles were seen pulling out of Ariha.

Ariha, which was home to 40,000 people before the conflict began, was the last remaining government-held city in Idlib province which borders Turkey.

The Army of Conquest coalition has won a string of victories in Idlib, including taking the provincial capital on March 28 and the key town of Jisr al-Shughur on April 25.