Aleppo/Beirut: The Syrian army pressed an offensive in Aleppo on Friday with ground fighting and air strikes in an operation to retake all of the city’s besieged rebel-held east that would bring victory in the civil war closer for President Bashar al-Assad.

“The advance is going according to plan and is sometimes faster than expected," a Syrian military source told Reuters, adding that the Syrian army and its allies had recaptured 32 of east Aleppo’s 40 neighbourhoods, about 85% of the area.

Reuters witnesses, rebels and a monitor on Friday confirmed the military thrust. There were no reports the Syrian army had made significant gains.

Russia’s Foreign Minister Sergei Lavrov said on Thursday that the Syrian army had halted military activity to let civilians leave rebel-held areas, RIA news agency reported.

But there was no sign on the ground that fighting had slowed and after Lavrov’s announcement, the army and its allies tried to advance on two fronts, a Turkey-based official with the Jabha Shamiya rebel group told Reuters.

“Helicopters, warplanes and rocket bombardment like every day. Nothing has changed," the official said, describing the situation as of 9:30 am local time (0730 GMT). The official added that despite the bombardment, “the guys are steadfast".

Russia’s air force and Iran-backed Shi’ite militias are also fighting in Aleppo on the government side. Rebel leaders have given no sign they are about to withdraw as the civilian population is squeezed into an ever-decreasing area.

The Russian military said on Friday it had helped more than 8,000 Syrian citizens flee parts of eastern Aleppo still controlled by rebels in the last 24 hours, including almost 3,000 children. This could not be independently verified.

Syrian government and allied forces have in the last two weeks driven rebels from most of their territory in what was once Syria’s most populous city. The rebels have controlled the eastern section since 2012, and Assad said in an interview published on Thursday that retaking Aleppo would change the course of the civil war across the whole country.

The Syrian government now appears closer to victory than at any point in the five years since protests against Assad evolved into an armed rebellion. The war in Syria has killed over 300,000 people, made more than half of Syrians homeless and created the world’s worst refugee crisis.

Rockets, bombs, artillery

The Syrian Observatory for Human Rights, which monitors the conflict, said government rocket attacks took place overnight into Friday morning on frontline areas of east Aleppo.

“There are aerial raids on the city’s neighbourhoods with highly explosive incendiary bombs, barrel bombs and artillery shelling," a fighter with the Nour al-Din al-Zinki rebel group on an eastern Aleppo frontline told Reuters.

“Thank God the situation is good and the rebels are repelling them, but the results are not apparent," he said.

Zakaria Malahifji, head of the political office of the Aleppo-based Fastaqim rebel group, speaking from Turkey told Reuters: “Lavrov spoke yesterday and his words were a lie. The bombardment did not stop at all through the night."

During a tour of Old Aleppo on Friday, which the Syrian army took control of this week, Reuters journalists counted the sound of nine air strikes in about half an hour.

There was widespread destruction in the UNESCO World Heritage Site, with fire-damaged ancient buildings, structures reduced to rubble and pieces of spent ordnance everywhere.

In rebel-held Aleppo, a Reuters witness said there were intense clashes on Friday in Sheikh Saeed district in the south of the eastern sector, where the Observatory and a Syrian military source said government forces advanced on Thursday.

Moscow and Washington are trying to negotiate a ceasefire to allow civilians to escape eastern Aleppo and let aid enter. Russia also wants the United States to urge rebel fighters to abandon their territory and accept transport out.

But rebels have so far given no indication they are ready to withdraw and this week called for an immediate five-day ceasefire and the evacuation of wounded and of civilians to other rebel-held territory.

“There are no negotiations now, except what’s being discussed internationally," Malahifji said. “We have asked for the evacuation of civilians who want to leave and of the injured. The fighters are determined to stay and face things."

Tens of thousands of people have been displaced since the offensive began two weeks ago, the United Nations has said. Many have passed into government-held areas.

Deep concerns over missing

The UN human rights office said on Friday hundreds of men from eastern Aleppo were missing after leaving rebel-held areas, voicing deep concern over their fate at the hands of government forces.

“Given the terrible record of arbitrary detention, torture and disappearances, we are of course deeply concerned," UN human rights spokesman Rupert Colville said. He said if reports were true that rebels had prevented some civilians from fleeing to safety it would be a potential war crime.

The government has dismissed reports of mass arrests, torture and extrajudicial killings by its forces as fabrications. Rebels deny they have prevented civilians from leaving opposition-controlled areas.

“The factions are facing very difficult choices," the Jabha Shamiya rebel group official said, adding:

“Yesterday the situation was a tragedy with all the meaning of the word. The situation was very bad. Firdous (neighbourhood) was heavily bombed, the people there were displaced, and you are talking about 50,000 people at least."

US Secretary of State John Kerry and Lavrov agreed by telephone on Thursday to keep discussing a ceasefire, but a Western diplomat told Reuters in Geneva it was hard to see another Kerry-Lavrov meeting taking place.

“The (U.S.-Russian) discussions make less and less sense. It’s not like an accord two months ago that would have been an evacuation of people so there would be fewer deaths," the diplomat said. “There will be heavy loss of life if the air strikes continue because the remaining people are in such a concentrated space now."

‘Nothing matters any more’

The humanitarian situation in rebel-held Aleppo, where food, water, fuel and medical care is scarce, is dire. All hospitals in the besieged sector have been repeatedly bombed out of service, local medics say, and treatment is given in makeshift clinics in houses or basements where possible.

A nurse told Reuters the situation was overwhelming. “There are no hospitals left in the first place ... I don’t know what to tell you."

A second senior official in the Syrian opposition said: “(The factions) can of course be steadfast, but the issue of the civilians is what is causing the pressure."

The United Nations estimates some 100,000 people are now squeezed into an “ever shrinking areas" of eastern Aleppo. The Observatory said there were about 120,000 people still living in rebel-held part of east Aleppo, based on information from local administrative bodies.

Before the latest offensive, besieged east Aleppo contained more than 250,000 people, according to the United Nations.

Ibrahim Samour, a pro-opposition local official in the rebel-held sector, said displaced people are wandering like nomads around the city under unrelenting bombardment.

“There isn’t much territory left with the rebels so the bombing is concentrated on several neighbourhoods," he said. “Nothing matters any more, not the international community, not human conscience, nothing."

Laila Bassam, Lisa Barrington, Tom Perry, Angus McDowall, Ellen Francis, Suleiman al-Khalidi and Stephanie Nebahay also contributed to this story.