Nusra Front, the Syrian affiliate of al Qaeda, said on Thursday it had taken over Ariha, the last city in the northwestern province of Idlib that was still held by the government.

The Sunni Muslim rebel group said it had overrun several checkpoints that defended the city, though Syria’s state army claimed the fighting was ongoing.

Nusra Front is the most powerful faction in Syria opposing both President Bashar al-Assad and the Islamic State militant group. In recent weeks, it has made gains in northwestern Syria, near the Turkish border, alongside other insurgent groups.

Nusra Front is now determined to seize the capital Damascus, its leader Abu Mohammad al-Golani said in a rare interview with news channel Al Jazeera this week.

“The mission of Nusra Front in the Levant is to topple Assad’s regime and all its symbols – its allies, I mean – such as Hezbollah and others, and to coordinate the establishment of a mature system of Islamic rule of law that Muslims can enjoy,” Golani s