Syrian army troops have killed 175 opposition fighters, many of them linked to al-Qaeda-linked groups, in an ambush described as one of the deadliest attacks by government forces near Damascus, according to state media. An opposition group alleged that Wednesday dawn's ambush was carried out by the Lebanese Hezbollah group, which has been instrumental in helping President Bashar al-Assad's regime push back rebels entrenched in the suburbs of the Syrian capital. Al Jazeera's Zein Basravi reports.