MOSCOW — Russia said on Wednesday that it would extend a moratorium on airstrikes in the Syrian city of Aleppo until Friday to give embattled antigovernment rebels a chance to leave the city and to “avoid senseless victims” of continued fighting.
Under terms of the cease-fire ordered by President Vladimir V. Putin of Russia, insurgents would be allowed to retreat “with their own arms” through two corridors between 9 a.m. and 7 p.m. local time on Friday. Six separate corridors were to be established for the evacuation of civilians and those needing medical attention.
Last month, Moscow was accused of war crimes by the United States and others as it unleashed the heaviest bombardment of the war in an effort to break the will of rebels and civilians surrounded by government forces in eastern Aleppo.
Moscow called off airstrikes on the city ahead of a three-day truce on Oct. 20 intended to let rebels and civilians leave. The effort largely failed, with both sides accusing the other of attacking anyone who tried to leave.
With a growing humanitarian crisis and the prospect of renewed bombing, the Kremlin is trying to find a way to persuade the rebels to quit Aleppo and in that way avoid a blood bath and a renewed round of criticism.
“All attempts by insurgents to break through in Aleppo have failed,” Valery V. Gerasimov, the chief of the Russian General Staff, said in a statement. “The terrorists have suffered heavy losses in lives, weapons and military equipment. They have no chance to break out of the city.”
One of the two exit corridors would lead to the border with Turkey, the other to the rebel-held town of Idlib, Syria, the military official said. The Syrian government has approved the decision and is prepared to pull back its army from the two corridors, the Russian Defense Ministry said.
Speaking to a group of top Russia experts last week, Mr. Putin said that his country was determined to rout the rebels from Aleppo, but was trying to avoid collateral damage.
“We keep hearing Aleppo, Aleppo, Aleppo,” he said. “Do we leave the nest of terrorists in place there, or do we squeeze them out, doing our best to minimize and avoid civilian casualties?”
In separate remarks on Tuesday, the Russian defense minister, Sergei K. Shoigu, blamed the West’s failure to cooperate with Moscow and to resist “terrorists” in Syria for an indefinite suspension in peace talks. Russia refuses to distinguish among groups fighting the government, considering all of them, even moderates backed by the United States, to be terrorists.
“The prospects for the start of a negotiation process and the return to peaceful life in Syria are postponed for an indefinite period,” Mr. Shoigu said.
Officials from Russia have repeatedly tried to deflect accusations that its military is adding to the carnage in Syria, saying its forces are there to support the legitimate government and to fight terrorism, along with distributing humanitarian aid.
At a recent news conference, Vitaly V. Naumkin, a Syria expert who also is an adviser to Russia in the United Nations, said the anti-Russia campaign in the West over Syria amounted to “hysteria,” including what he called exaggerated casualty figures.
Russia wanted to help establish the conditions needed for national reconciliation, he said, which it considers the only path out of the war. “We have our common enemy, terrorism, that it is what we have to fight against,” Mr. Naumkin said.
Despite an almost complete breakdown in talks with the Obama administration over Syria, Mr. Naumkin said he would travel to the United States this week for discussions in Washington about resuming cooperation.
