Over 20 rebels were killed Wednesday while booby-trapping a car in Syria's northern province of Aleppo, the pan-Arab al-Mayadeen TV reported.

The car went off while the rebels were booby-trapping it near the town of Hraitan in the northern countryside of Aleppo, said the report, spelling no further details.

Separately, the oppositional Syrian Observatory for Human Rights said the Syrian air force carried out at least 211 air raids on several Syrian areas over the past 24 hours.

The airstrikes targeted areas in the countryside of the capital Damascus, the northern provinces of Aleppo and al-Raqqa, the eastern province of Deir al-Zour and the southern province of al-Qunaitera, according to UK-based Observatory.

It said that 80 civilians were killed and hundreds of others wounded during the strikes. The account, however, couldn't be independently verified.

The Syrian crisis has been dragging on since nearly four years ago with no sign of abating.

Political efforts have recently been exerted by Russia to bring the government and the opposition around the negotiation table in Moscow later this month in the hope of paving the way for ending the conflict politically.