Government pounds rebel-held areas as the bloody four-year stalemate over key city appears to be coming to an end.

Government forces continue to advance in the besieged city of Aleppo, pushing opposition forces out of several areas in the latest twist in the six-year-old Syrian conflict.

Syrian warplanes, artillery, and mortar rounds on Saturday pounded opposition-held areas in eastern Aleppo, killing at least three people, according to opposition activists.

Syrian state media reported government and allied troops were moving in on new neighbourhoods, pushing a kilometre deeper into the rebel-held enclave.

How much longer can east Aleppo hold out?

Syrian army spokesman Brigadier General Samir Suleiman said the military has regained control of 45 to 50 percent of east Aleppo, and he accused rebels of hiding among civilians.

The advances have caused massive displacement. The UN estimated more than 31,000 have already fled their homes, either to government or Kurdish areas, or deeper into the besieged enclave.

Residents in eastern Aleppo also reported intense shelling in al-Sukkari neighbourhood on the southern edge, where many of the newly displaced have sought refuge.

“The noose is tightening quickly,” said Mohammed Abu Jaafar, a medical official in eastern Aleppo. “Our resources are also running low and beginning to disappear.”

Syria’s defence minister and other senior officers visited newly captured areas in Aleppo on Saturday, according to state-run media.

Russian support has helped President Bashar al-Assad’s forces drive the fighters out of several neighbourhoods during the ongoing offensive.

“We are told that around 50 percent of the rebel-held eastern Aleppo is now held by the government forces and its allies,” Al Jazeera’s Stefanie Dekker, reporting from Gaziantep on the Turkey-Syria border, said.

“This is the first time that we see this happening in four years. Aleppo has been in a stalemate between the government forces and rebels. Activists say that Aleppo is the heartland of this revolution and if they lose this city, they would lose their civilisation, they would lose everything.”

Syrian forces tighten grip on besieged Aleppo

More than 300 civilians have been killed in the area since the government resumed its offensive to remove the fighters on November 15, according to activists.

The Russian Interfax news agency report quoted an unnamed Syrian military official as saying a light ground attack aircraft, L-39 jet, was shot down near Aleppo, and its crew was killed.

The opposition Britain-based Syrian Observatory for Human Rights, which relies on a network of activists on the ground, said two pilots were killed when rebel fighters attacked the aircraft as it approached Aleppo airport to the east of the city.

Asked about reports of the downed plane, Suleiman said “we have no such information about such an incident, and when such things happen the army announces them”. He was speaking to reporters in Aleppo.

Against this backdrop of continued fighting, Russia announced on Saturday it was ready to hold quick talks with the United States on the exit of opposition fighters from Aleppo.

However, a rebel official said commanders in eastern Aleppo will not surrender to government forces.

“I asked the factions, they said ‘we will not surrender’,” said Zakaria Malahifji, the head of the political office of the Aleppo-based Fastaqim faction, speaking from Turkey.

“The military commanders in Aleppo said ‘we will not leave the city. There is no problem with corridors for civilians to leave, but we will not leave the city’,” he said.