Aleppo saw one of its bloodiest days since the ceasefire began on Friday, as government forces laid the groundwork for a “war of all wars” to retake Syria’s second city.

The carnage of the last few days has propelled Aleppo - bitterly contested since 2012 and considered the jewel of Syria - once again to the main battlefield in the civil war.

The Syrian regime pounded rebel areas in the city with air raids, including on another medical clinic, while opposition fighters hit government-held neighbourhoods with rocket and artillery fire.

Friday prayers were cancelled across Aleppo for only the second time during the five-year war, so worried were residents that they would be targeted if they gathered in groups.

• Syrian and Russian forces 'preparing to liberate Aleppo'

With more than 100 killed in the past 48 hours, an average of one Syrian was dying every 25 minutes.

An Arabic hashtag translating as "Aleppo is burning" was re-tweeted hundreds of thousands of times on Twitter yesterday alongside pictures of children being pulled from smoking rubble.