Beirut: A Syrian military helicopter was shot down over the last major rebel bastion in northwest Syria on Friday, killing two pilots, a war monitor said, in the second such incident this week.

The Syrian Observatory for Human Rights said the aircraft was downed over the western countryside of Aleppo province where government forces have scored major gains against rebels and extremists in recent weeks.

The Britain-based monitor blamed the attack on rebel-backer Turkey but there was no immediate claim of responsibility.