UN special envoy for Syria 'appalled' that rebels target civilians in Aleppo

The UN special envoy for Syria says he is "appalled and shocked" that rebels in western Aleppo are targeting civilians in the city.

Staffan de Mistura says "relentless and indiscriminate" rocket attacks have killed scores of civilians in the past 48 hours - which could amount to war crimes.

On Friday, rebels began an offensive aimed at breaking the government siege of east Aleppo.