Opposition activists say that insurgents in Syria have captured the last military base in the northwestern province of Idlib, marking the latest collapse of government troops in the region.

The Britain-based Syrian Observatory for Human Rights said factions — including al-Qaida's branch in Syria, the Nusra Front, and the ultraconservative Ahrar al-Sham — captured Mastoumeh base Friday, after days of fighting.

The Observatory says government forces left the base and withdrew to the nearby town of Ariha.

State-run Syrian TV said army units in Mastoumeh base were moving to reinforce defenses in Ariha further south.

Government troops withdrew from the provincial capital of Idlib after it fell to opposition fighters in March, followed by the strategic town of Jisr al-Shughour and Qarmeed military base days later.