Syrian forces close in on crucial Shaar district as Damascus and Russia pledge to “destroy” rebels who don’t leave.

Syrian forces were on the verge of seizing a key rebel-held district of east Aleppo on Tuesday as Damascus and ally Moscow warned that rebels who failed to leave the city peacefully would be destroyed.

After retaking control of about two-thirds of opposition-held east Aleppo over the past week, forces loyal to President Bashar al-Assad advanced on the large residential district of Shaar. With the capture of Shaar, the army would hold nearly 70 percent of east Aleppo, four years after rebels first seized it and divided the ancient city.

In Damascus, the Foreign Ministry said in a statement carried on the state SANA news agency that the government would not allow rebels a chance to “regroup and repeat their crimes” in Aleppo.

On Monday, Russia and China blocked a draft resolution at the UN Security Council demanding a seven-day truce in Aleppo to evacuate the sick and wounded, and to provide humanitarian aid workers time to get food and medicine in.

Russia, a main backer of the Syrian government supporting the government’s offensive in the city, has repeatedly blocked action in the Security Council over Syria.

“Those who refuse to leave nicely will be destroyed,” Russian Foreign Minister Sergey Lavrov told reporters in Moscow, speaking of the Syrian rebels. “There is no other way.”

The Britain-based Syrian Observatory for Human Rights , a monitoring group, said if Shaar district is retaken rebel forces will be reduced to a “war of attrition” with the army.

“It is the most important neighbourhood in the heart of east Aleppo, and is on the brink of falling,” Syrian Observatory head Rami Abdel Rahman told AFP news agency, adding that regime forces were already in control of a third of the district.

The government’s rapid gains have left opposition fighters scrambling to defend the shrinking enclave they still control in Aleppo’s southeastern districts.

“The frontlines are moving. Yesterday, the Syrian government and its allies made significant headway in the east, reaching about 800 metres away from the old citadel that the government holds as well, and almost practically cutting what is left of the rebel-held area in half,” Al Jazeera’s Stefanie Dekker said, reporting from Gaziantep along the Turkey-Syria border.

The international community has also struggled over how to respond, despite widespread concern over the fate of tens of thousands of civilians still in rebel-held areas, many of whom have been left with little-to-no shelter.

‘Attempt to buy time’

Russia had announced talks with the United States in Geneva for Tuesday or Wednesday with the intent of organising a full rebel withdrawal from Aleppo leading to a ceasefire.

But the government in Damascus on Tuesday said it would not agree to a ceasefire in Aleppo unless it guarantees a full withdrawal of rebel factions from the city.

“Syria will not leave its citizens in east Aleppo to be held hostage by terrorists, and will exert every effort to liberate them,” said the foreign ministry statement.

“It therefore rejects any attempt by any side to reach a ceasefire in east Aleppo that would not include the exit of all terrorists.”

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Lavrov accused Washington, which has backed rebel groups against Assad, of backtracking.

“It looks like an attempt to buy time for the rebels to have a breather, take a pause and replenish their reserves,” Lavrov told journalists, adding that Moscow had the impression that “a serious discussion with our American partners isn’t working out”.

Washington, for its part, accused Moscow of stalling for time after Russia and China blocked the UN Security Council resolution calling for a seven-day ceasefire.

The rebels have so far rejected any talk of leaving the city, with Yasser al-Youssef of the leading Nureddin al-Zinki faction describing the proposal as “unacceptable”.

Key battleground

The loss of Aleppo would be the biggest blow yet to opposition forces in Syria’s nearly six-year civil war, which erupted in March 2011 with popular protests calling for Assad’s ousting.

At least 400,000 people have been killed since violence began and millions have been forced from their homes.

Aleppo, once Syria’s celebrated commercial and cultural hub, has been a key battleground of the war and suffered some of its worst violence.

The most recent offensive has left more than 341 people dead in east Aleppo, including 44 children, the Syrian Observatory says.

Rebel fire into the government-held west of the city has killed 81 people, including 31 children, in the same period.

Tens of thousands of east Aleppo residents have also fled to different parts of the city, including to government-held areas in the west and other rebel neighbourhoods.

Increasing bombardment of the neighbouring opposition-held province of Idlib has also left dozens dead in recent days.