The United States says the assault on Aleppo is proof that President Bashar al-Assad and his Russian and regional allies have abandoned an international peace process.
A diplomatic solution to the fighting looked unlikely as US and Russian diplomats disagreed at a UN Security Council meeting called to discuss the violence.
President of Open Doors UK & Ireland, Eddie Lyle, speaks to Christian Today about the worst places to be a Christian, and why it's time for the Church to speak up.
US-led coalition air strikes reportedly killed dozens of Syrian soldiers on Saturday, endangering a US-Russian brokered ceasefire and prompting an emergency UN Security Council meeting as tensions between Moscow and Washington escalated.
Syria's ceasefire "will not hold out", a senior rebel official in Aleppo warned on Saturday, as air strikes and shelling continued in some places and promised aid deliveries failed to come through.
Russia said the Syrian army had begun to withdraw from a road into Aleppo on Thursday as the government and rebels accused each other of violating a truce.