Children look at the rubble of damaged buildings in a rebel-held area of Aleppo on Sunday. (Abdalrhman Ismail/Reuters)

The last of stockpiled rations were distributed Thursday in east Aleppo, and widespread starvation is expected to set in as winter arrives if no progress is made in negotiations to deliver food and medical aid, the United Nations said.

“It is terrible as we speak; it could get much worse,” U.N. relief envoy Jan Egeland said in Geneva. “I do not think anybody wants a quarter of a million people to be starving. . . . I cannot see anyone wishing to see so many civilians bleed to death . . . because of indiscriminate war.”

Russia said it would continue, at last through Friday, what has been a pause of several weeks in its air attacks. But it said that it and the Syrian government — which occupies western Aleppo and surrounds the entire city — would not fail to respond to ongoing shelling and other ground attacks by rebel forces in the east.

Egeland said that “tremendous ground fighting” between the two sides has stopped repeated plans to deliver aid to civilians and evacuate the wounded.

He pleaded with Russia and the United States to continue trying to negotiate some form of cease-fire. “It is only when these two . . . have been leading that we have made progress, when we have not been completely stalled,” Egeland said.

Planned humanitarian convoys have yet to deliver aid, he said, because of the danger and the inability to obtain simultaneous security guarantees from all sides. A new U.N. proposal was delivered to the United States, Russia and other actors early this week.

“Syria is the worst war, the worst humanitarian crisis, the worst displacement crisis, the worst refu­gee crisis in a generation” Egeland said. While there has been no contact with the incoming Trump administration, he said, “we expect U.S. help and engagement to be continued, uninterrupted, in the coming months.”

But U.S.-Russia engagement, despite months of negotiations over a cease-fire in Aleppo and beyond, has made no progress in ending sieges across western Syria, largely by surrounding government forces, or in moving toward a transition government that both have said is their long-term goal.

In Moscow, Deputy Foreign Minister Sergei Ryabkov said that Russia would continue to work with the new administration on Syria, but that “it would be exaggeration and wishful thinking to say that we are on the threshold of some radical change for the better.” In an interview with the Russian news agency Interfax, Ryabkov suggested that repeated delays in initiating a political process in Syria were largely Washington’s fault.