six-storey apartment building was destroyed this week.

With government forces mounting their most concerted effort yet to capture the rebel-held east, these are the darkest days for the opposition in Aleppo since the beginning of the uprising against President Bashar al-Assad in 2011.

Backed by Russian air support, the Syrian army and allied Shi’ite militia from Iran, Lebanon and Iraq have gradually blockaded the rebel-held east of the city this year, first cutting the northern lifeline to Turkey and then fully encircling it from the west and south.

Pro-government forces identified as Shi’ite militias by the rebels have in recent days launched a ground attack aiming to split the rebel-controlled territory by seizing areas including Hanano, where fierce battles were underway on Friday.

The fall of eastern Aleppo would be the biggestRussia and Damascus.

Asked about any “Plan B”, he replied: “In many ways Plan B is that people starve”. He said that could not be allowed to happen.

The government has besieged numerous rebel-held areas of Syria throughout the war that has killed hundreds of thousands of people, and the country has become partitioned into a patchwork of zones controlled by various combatants.

A number of the besieged areas near Damascus have succumbed to the government pressure in recent months, with rebels leaving to the northeastern province of Idlib in negotiated agreements with the government.

The desperation in eastern Aleppo has started to surface.

A brawl erupted last week outside the warehouse of a foreign charity that had been forced to suspend its distribution of food aid parcels as its supplies dried up.