Pro-Syrian government forces attacked rebel-held areas of Aleppo on four fronts on Tuesday in their biggest ground assault since the military launched an offensive to take back the whole city last week, a senior Syrian rebel official told Reuters. Separately, an Iraqi militia commander fighting in support of the government told Reuters a large army force, spearheaded by an elite unit known as the Nimr, or Tiger Forces, had started to move in armoured vehicles and tanks for an attack on rebel-held districts of eastern Aleppo.