Damascus, Sep 1 (IANS): At least 50 rebels, mainly commanders, were killed on Saturday by US-led airstrikes that targeted a meeting of rebel commanders in Syria's northwestern province of Idlib, a war monitor reported.

The Syrian Observatory for Human Rights said the meeting grouped commanders of the Hurras al-Deen and Ansar al-Tawhid groups, both allied with the al-Qaida, Xinhua news agency reported.

It said the death toll exceeds 50, noting that more bodies are being discovered.

The Britain-based watchdog group said the US-led coalition targeted the meeting with at least seven highly explosive missiles.

The US Central Command confirmed that it had attacked leaders of al-Qaida in Idlib province, noting that the operation had targeted those "responsible for attacks threatening U.S. citizens, our partners, and innocent civilians."

The US airstrike comes as a cease-fire was declared by the Syrian army on Friday and went into effect on Saturday.

The new cease-fire aims at halting the fighting in Idlib between the Syrian army and the al-Qaida-linked groups.