GENEVA — The United Nations will resume talks with the Syrian government next week in the hope of achieving a cease-fire around Aleppo, the largest city in the north, the special envoy for Syria said Thursday. But the specifics remained hazy.

“We are aiming at a reduction of violence and possibly a freeze of all military activities,” the envoy, Staffan de Mistura, said in Geneva. “Our hope is that Aleppo could be a signal of good will, a confidence-building measure which could and can facilitate the restarting of a political process with a clear political horizon.”

He said world leaders had agreed on the need to break the deadlock in Syria and halt a civil war that he said had left over 220,000 dead, a million wounded and millions more displaced. Yet the response to proposals for a freeze around Aleppo has so far been tepid from both the Syrian government and opposition factions.