BEIRUT - Syrian activists say government forces set off explosives planted at a farm where Islamic rebel factions were gathering, killing 17 militants.

The Britain-based Syrian Observatory for Human Rights says the explosion took place late Saturday in the village of Kfar Shams in southern Daraa province.

Ahmad al-Masalmeh, a Daraa-based opposition activist, said Sunday that a farm in the village was booby trapped and the explosives were detonated once the militants had gathered there.

Syria's state news agency reported that several fighters of the Islamic Muthana Movement were killed and two of their "dens were demolished at Kfar Shams."

The latest killings deal another blow to Syria's Islamic rebels, just days after the assassination of a powerful rebel leader.