BEIRUT — Syrian rebels fought government forces north of the divided city of Aleppo Wednesday as both sides sought to expand their ground amid a push by the UN envoy to the country to broker a cease-fire in the city.
The clashes began with a government offensive launched a few hours before the envoy, Staffan de Mistura, said President Bashar Assad expressed a willingness to suspend bombing of Aleppo for six weeks.
The hiatus would set the stage for a proposed UN plan to ‘‘freeze’’ hostilities in Syria’s largest city. However, rebels and opposition activists said that they are deeply skeptical — based on past experience and similar failed peace efforts — that the government would abide by any truce.
‘‘The regime says it wants dialogue then attacks rebel positions,’’ said Bahaa Halaby, an activist in Aleppo. He said fierce clashes were taking place north of the city Wednesday.
Syrian government forces backed by Shi’ite fighters, including the Lebanese Hezbollah group, launched a surprise offensive on Tuesday, capturing several villages that brought them closer to their goal of cutting off the main supply route to rebels in Aleppo and besieging opposition-held areas.
More than a hundred people on both sides were killed by Wednesday, in a counteroffensive in which rebels regained much of the territory they lost a day earlier, activists said.
An amateur video released by rebels showed the bodies of at least 25 Syrian soldiers and pro-government gunmen in Aleppo’s northern suburb of Mallah, scattered in a muddy open field. The video appeared genuine and corresponded to other reporting of the violent clashes taking place.
Progovernment TV channels, in turn, ran footage showing troops running behind tanks in smoke-filled fields and fighters driving vehicles mounted with heavy machine guns to the backdrop of nonstop gunfire and explosions.
A few hours after the government offensive started Tuesday, de Mistura offered a glimmer of hope on his efforts to find a solution to Syria’s civil war, telling the UN Security Council at a briefing that Assad had agreed to halt airstrikes and artillery shelling of Aleppo for six weeks.
‘‘Let’s be frank, I have no illusions because based on past experiences this will be a difficult issue to be achieved,’’ de Mistura said. He added, however, that he would return to Damascus ‘‘as soon as possible’’ to announce a start date.
Rebels claimed the government offensive proved that Damascus was not serious and said they have serious doubts about how a freeze in hostilities could take place in a city that was once Syria’s commercial capital and is now a wasteland and mosaic of various rebel groups.
Ahmad Hamed, an activist in Aleppo, said he believed most rebel factions will abide by a truce if the government halts airstrikes and releases detainees, starting with female prisoners. Speaking via Skype, he and other Aleppo-based activists said militants from the Nusra Front — Syria’s Al Qaeda branch, which has a small presence in the city — are not expected to abide by the plan.
The Islamic State group is also about 18 miles northeast of the city.
Still, there were signs that most rebel factions might be at least willing to engage on the plan and see whether the government will make good on its pledge to de Mistura.
Two and a half years of fighting in the city has exhausted fighters and destroyed rebel-held neighborhoods.