The Britain-based Syrian Observatory for Human Rights said Mannagh helicopter base fell nearly 24 hours after rebels, led by al-Qaida-linked militants, launched an all-out offensive against it. The Aleppo Media Center said rebels finally captured it before dawn.
Mannagh, in the north of Aleppo province, is deep inside territory dominated by the Syrian opposition. Rebels have been trying since last year to capture it, but faced strong resistance from defenders.
The Observatory said the final assault on Mannagh was led by members of the al-Qaida-linked Islamic State of Iraq and the Levant. It began early yesterday when a Saudi suicide attacker blew his vehicle up outside the command center of the sprawling compound.
It said the rebels then began advancing, capturing vehicles and buildings inside the base. It did not say how many government troops were killed but said at least 10 rebels, including foreign fighters, died in the fighting.
The fall of Mannagh followed the rebel capture of four villages in the heartland of Assad's minority Alawite sect on the country's Mediterranean coast. Rebel victories have otherwise been comparatively rare in recent months, and Assad's forces have been on the offensive in the center of the country.
More than 100,000 people have been killed since Syria's conflict started in March 2011 as largely peaceful protests against Assad's rule. After opposition supporters took up arms to fight a brutal government crackdown on dissent, it turned into an armed uprising and later escalated into a civil war.