Russia and Syria halted airstrikes on the Syrian city of Aleppo on Tuesday to give civilians and militants a chance to leave rebel-held districts this week, Russia's defence minister said, according to news agency TASS.
Russian Defence Minister Sergey Shoigu said the cessation of air raids was necessary to allow Russia to carry out a "humanitarian pause," planned for Thursday, to allow the evacuation of rebel-held areas via special corridors.
But Ousama Abu Zeid, the legal adviser of the opposition group the Free Syrian Army, ruled out that any fighter would leave Aleppo.
"This is their land and they will never leave it or surrender," Zeid told dpa. "The idea of evacuating their own land is out of the question."
"We are continuing with the struggle," Zeid added.
Russia intervened in Syria about a year ago to prop up President Bashar al-Assad's crumbling army, which had been fighting rebel forces since 2011.
Russia's air campaign enabled government forces to reclaim territory from both rebels and the Islamic State extremist group.
Some 250,000 to 300,000 civilians are thought to be trapped in eastern Aleppo, which suffers from dwindling food supplies and extremely limited medical care. Hospitals have repeatedly been hit in airstrikes.
The UN Human Rights Council said it would hold an emergency session on Friday to discuss the worsening situation in the embattled city.
The special meeting was called by a group of countries including Germany, France, Italy, Britain, the United States, Turkey, Saudi Arabia and Kuwait, the council's spokesman said.
The group stated in a letter that it sought the session "following the most recent deterioration of the human rights situation in Aleppo, and the failure of the [Assad] regime and its allies to fulfil their international human rights commitments."
Russia was not among the countries that supported the emergency gathering, according to a list provided by the spokesman.
Western nations charged that war crimes are likely being committed and have urged Russia to halt attacks on civilian targets.
Moscow has claimed for some time that there are routes out of eastern Aleppo, though pro-opposition activists deny this, saying civilians are trapped.
Russia has previously announced the creation of safe passages from eastern Aleppo, but only a very small number of civilians are thought to have taken advantage of them.
"The people in besieged eastern Aleppo will not use a corridor only supervised by Russia and the regime," Rami Abdel Rahman, the head of the Britain-based Syrian Observatory for Human Rights, told dpa.
"They want a corridor supervised by the UN," Rahman said.
The UN has previously said people in eastern Aleppo fear crossing at government-designated safe passages, noting that Syrian army units are stationed at these crossings, located on the front lines of the divided city.
"We need all assurances before we can do anything meaningful – such as evacuating the sick and wounded and to bring anything into the city which has been under siege," Jens Laerke of the UN Office for the Coordination of Humanitarian Affairs (OCHA) said in Geneva.
"So far, we have not received assurances from all sides," Laerke added.
Meanwhile, activists in eastern Aleppo confirmed that airstrikes had stopped around dawn, in line with what the Russians announced. Moscow said al-Qaeda-linked militants are located in eastern Aleppo.