 -- Russia's military said today that Syrian government troops have pressed into rebel-held areas of the besieged city of Aleppo, as a two week-long offensive there grinds forward, sending hundreds of civilians fleeing and appearing to push rebel defenders closer to defeat.

Syrian state-controlled media announced that troops loyal to the regime of Bashar al-Assad had seized two keys neighbourhood in the city, threatening to split the rebel-held east of the city into two parts. Syrian troops captured the Jabal Badro neighborhood a day after they took another, Hanano, bringing them close to being able to drive a wedge that would separate the southern areas held by rebels from those they control in the north, the BBC reported.

Russia's defense ministry said Syrian government troops had taken Hanano, as well as four other neighborhoods. Journalists in Aleppo reported that shelling and airstrikes were hammering rebel defenses in new areas and that hundreds of civilians were fleeing the government advances, moving to the regime-controlled West the city.

The Syrian Observatory for Human Rights, a UK-based group that monitors the conflict, said 500 civilians had fled the rebel-held east of the city over the weekend; Russia's military claimed more than 900 had left from one area alone. The Observatory said 219 civilians had died since the offensive began, including 27 children.

"Thing in eastern Aleppo very, very bad," Khaled Khatib, a photographer for the White Helmets group that rescues people in Syria from buildings collapsed by airstrikes, wrote on Twitter. "Aleppo will die," he wrote.

The government gains bring the Assad regime another step closer to re-taking Aleppo, Syria’s second largest city, the eastern part of which has been held by rebels since 2012 and which has been under siege for months. Around 275,000 people are trapped in the city, according to the UN, living under daily government bombing and enduring acute shortages of food and medical supplies.

Backed by heavy Russian air strikes, government forces along with fighters from Lebanon and Iran have encircled the eastern part of the city and are now tightening the noose, breaking through rebel front lines and taking areas controlled by the opposition since 2012. A mixture of more moderate opposition groups are fighting alongside radical jihadists militants to try to halt the advance.

On Sunday, opposition groups said government troops were now moving on the Sakhur neighborhood, which if it falls would cut the rebel-held zone in two.

Yasser al-Youssef, from the rebel group Nour al-Din al-Zenki, told AFP that opposition fighters were shoring up defenses in the area.

"We are strengthening our positions to defend the city and residents, but the aircraft are destroying everything methodically, area by area," he said.

Eastern Aleppo has been under total siege since late summer and residents are now living in increasingly dire conditions, with food and medical supplies running out. A week ago, the World Health Organization said the last hospitals in Aleppo had been forced to stop operating after they were bombed. The UN, which was last able to distribute rations on November 13, has pleaded to be allowed to deliver emergency aid to the city, but has been refused by the Syrian government.

Asked by reporters if there was any Plan B if the aid was not resumed, a UN relief adviser, Jan Egeland, said: "In many ways Plan B is that people starve." Egeland said that must not happen.

The fall of Aleppo would be a major victory for Assad and his ally Russia, whose intervention in September last year has pulled the Syrian president's regime back from the brink of collapse. Since November, Russia has intensified its bombing campaign across Syria, as the government has appeared increasingly emboldened.

Efforts by the U.S. to broker ceasefires for Aleppo fell apart in September and Moscow and the Assad regime appear determined to retake the city, despite protests from Western countries that they are committing war crimes by indiscriminately bombing civilians and targeting hospitals.

The Obama administration has warned Russia no military victory is possible in Syria, but Assad has repeatedly said he will take back all areas of the country.

A representative of an opposition group that Moscow backs in now stalled peace negotiations, said no further talks were possible until Aleppo had been retaken. Qadri Jamil, a member of the so-called Moscow-Astana Opposition, which contains former Syrian government figures and closely follows Russia's public positions on the conflict, said he expected the city to fall before the end of the year.

The UN has condemned the government offensive, with the head of its emergency relief program, Stephen O'Brien saying the bombardments were exceptional in their brutality.

"Let me be clear: we are not just seeing a resumption of violence in Aleppo, this is not business as usual," O’Brien said in a statement last week. "What has been unleashed on civilians this past week is yet another low in an unrelenting inhuman onslaught."