Russia's defence ministry on Thursday dismissed as "counterproductive" a request from the United Nations to extend future pauses in fighting to allow aid into rebel-held eastern Aleppo as winter comes.
The ministry said it received a request from the head of a UN-backed humanitarian taskforce for Syria, Jan Egeland, to make future breaks in fighting longer to allow in aid supplies.
But Russia in a statement quoting spokesman Igor Konashenkov said it was "counterproductive and against common sense" to extend the ceasefires "just for the sake of it, not to bring real help to peaceful civilians, but so that terrorists can better restore their battleworthiness".
Egeland earlier Thursday warned that the "last food rations" were now being distributed in eastern Aleppo after four months of deadlock.
"I don't think anybody wants a quarter of a million people to be starving in east Aleppo," Egeland said, referring to the number of civilians the UN says are living under siege.
Russia has held a series of unilateral ceasefires that saw Syrian forces on the ground halt fire to allow rebels and civilians to quit east Aleppo, although very few have done so, with many expressing scepticism about the declared safe passages.
Russia held a 10-hour pause in fighting on November 4 and a three-day truce in late October.
Russia said Thursday that it had brought more than 100,000 tonnes of humanitarian aid to Aleppo in recent months "irrespective of any humanitarian pauses".
"Those who really want to help the residents of Aleppo, are helping them," the ministry said. Russia, a long-term ally of Syrian President Bashar al-Assad, launched air strikes to back up his forces in September last year.
Moscow says it has halted airstrikes on east Aleppo since October 18 after a month-long ferocious bombardment of Syria's second city that killed hundreds of civilians and hit health facilities, sparking international condemnation.