Syrian regime forces were on the defensive around Aleppo yesterday after a rebel alliance said it inflicted a major setback by breaking a three-week government siege of the battered city.

A coalition of rebels and jihadists surged through regime territory on Saturday to open a new route into Aleppo's besieged eastern neighbourhoods, home to an estimated 250,000 people.

The breakthrough was met with euphoric scenes among civilians and opposition fighters in eastern districts, but sparked fear of food shortages among residents of regime-controlled western areas.

Rami Abdel Rahman, head of the Syrian Observatory for Human Rights, said the development was one of the most significant setbacks for government forces since the conflict erupted

in March 2011.

"Despite more than 600 Russian strikes, the regime forces were not able to hold on to their positions," he said.

Reports said Syrian regime forces were redeployed yesterday to try to

avoid being surrounded in neighbourhoods they control in Aleppo. State media denied that the siege had been broken and that its own forces were surrounded, saying the battle for Syria's second city was ongoing.

The Observatory said there were intermittent air strikes and clashes on the southern edges of the city yesterday, where the opposition alliance overran a series of buildings in a military academy the previous evening.

Yesterday, rebel forces brought seven pick-up trucks full of fruit and vegetables into the eastern districts of Aleppo to be distributed to local markets, an opposition fighter said.

The fight for Aleppo is among the fiercest so far in Syria's chaotic multifront war, which has killed more than 280,000 people. The Britain-based monitor said at least 130 civilians and 700 fighters from both sides have been killed since the opposition alliance launched its offensive on southern Aleppo on July 31.

Syria's former al-Qaeda affiliate said it had seized huge caches of weapons from regime forces in the artillery school south of Aleppo.