Rebel-held east Aleppo is facing renewed air strikes and artillery shelling from Russian-backed government forces in what is expected to be a final push designed to quash the opposition in the city for good.

Activists inside the regime siege barricades said they were sent text messages from the government in the early hours of Sunday to evacuate before a “strategically planned assault using high precision weapons occurs within 24 hours.”

Artillery shelling on Sunday night reportedly targeted Fardous and Salheen neighbourhoods, killing at least six people, including a five-year-old girl.

Russia declared a moratorium on air strikes on east Aleppo which began on 18 October, announced after a month of unprecedented bombing which killed an estimated 500 people in one of the bloodiest chapters of the almost six-year-long civil war.

The pause was to allow the area’s 250,000 trapped civilians and 8,000 rebels – among them al-Qaeda allied factions – to leave through humanitarian corridors into the government side of the city under the terms of an amnesty. Both sides have accused the other of targeting checkpoints with sniper and mortar fire, meaning very few people have managed to flee the bombing.

Nato intelligence as well as Russian military sources have said that October’s huge deployment of missile-carrying Russian ships and submarines to the Syrian coast is “ready” to assist Syrian President Bashar al-Assad in the renewed assault.

The surrounding rebel-held territory in Aleppo province and neighbouring Idlib was not included in the moratorium and has been pounded by Russian and regime strikes in the past few weeks, including the bombing of a school on 27 October which killed at least 22 children.

Dahiyet al-Assad - Aleppo Show all 16 1 /16 Dahiyet al-Assad - Aleppo Dahiyet al-Assad - Aleppo A girl who fled areas of conflict rides a vehicle in Dahiyet al-Assad, west Aleppo city, Syria REUTERS/Ammar Abdullah Dahiyet al-Assad - Aleppo Rebel fighters from the Jaish al-Fatah (or Army of Conquest) brigade have a tea in a building under construction Getty Dahiyet al-Assad - Aleppo A rebel fighters' armoured vehicle in Dahiyet al-Assad Reuters Dahiyet al-Assad - Aleppo Rebel fighters from the Jaish al-Fatah (or Army of Conquest) brigades sit on a tank Getty Dahiyet al-Assad - Aleppo Abandoned magazine of shells after rebel fighters took control of Dahiyet al-Assad Reuters Dahiyet al-Assad - Aleppo Rebel fighters ride a pick-up truck with civilians who fled areas of conflict in Dahiyet al-Assad, west Aleppo city, Syria Reuters Dahiyet al-Assad - Aleppo A rebel fighter gestures with a girl who fled areas of conflict while they ride a pick-up truck in Dahiyet al-Assad Reuters Dahiyet al-Assad - Aleppo Smoke rises near a damaged road in Dahiyet al-Assad, west Aleppo city, Syria Reuters Dahiyet al-Assad - Aleppo Syrians carry their belongings as they leave the southwestern frontline neighbourhood of Dahiyet al-,Assad Getty Dahiyet al-Assad - Aleppo A view shows a damaged minaret of a mosque after rebel fighters took control of Dahiyet al-Assad, Syria Reuters Dahiyet al-Assad - Aleppo Rebel groups have pledged to push from newly captured positions in the Dahiyet al-Assad district towards Hamdaniyeh. Rebels and allied jihadists launched a major offensive on October 28, 2016 to break through government lines and reach the 250,000 people living in the city's east Getty Dahiyet al-Assad - Aleppo Rebel groups have pledged to push from newly captured positions in the Dahiyet al-Assad district towards Hamdaniyeh Getty Dahiyet al-Assad - Aleppo Rebel fighters from the Jaish al-Fatah (or Army of Conquest) brigades hold a position at an entrance to Aleppo, in the southwestern frontline neighbourhood of Dahiyet al-Assad Getty Dahiyet al-Assad - Aleppo Smoke billows from the frontline district of Dahiyet al-Assad following an attack by rebels on Syrian regime forces in the northern city of Aleppo Getty Dahiyet al-Assad - Aleppo Syrians carry their belongings as they leave the southwestern frontline neighbourhood of Dahiyet al-Assad Getty Dahiyet al-Assad - Aleppo People who fled areas of conflict ride a pick-up truck in Dahiyet al-Assad, west Aleppo city, Syria Reuters

A counterattack launched by rebels last month intended to break the siege has all but failed, as government forces have recaptured Aleppo’s Assad neighbourhood and the village of Minyan outside the city, the UK-based Syrian Observatory for Human Rights said on Sunday.

At least 100 civilians in west Aleppo have been killed by rebel rockets launched at the government-controlled territory.

The divided city has been the scene of intense fighting since 2012 but has escalated into a full-scale catastrophe since the regime managed to cut off rebel supply lines in July, leaving residents on the east side living under siege conditions.

Last week the UN warned that residents in opposition neighbourhoods will starve this winter unless urgently needed aid is allowed in.