BEIRUT — A wave of airstrikes has killed more than 90 people over two days and deepened mistrust among Syrians that a cease-fire, due to take effect Monday, will deliver on its promise to ground the Assad government warplanes.
Syrian armed opposition groups are still debating whether to accept the terms of the deal, which calls for a complete halt to violence for seven days, followed by joint operations by the United States and Russia against designated terrorist groups such as the Islamic State and the former Nusra Front.
Opposition groups — including those strongly against Al Qaeda and the Islamic State — widely believe the deal is stacked against them. And some government supporters also distrust it.
The Ahrar al-Sham group Sunday condemned the superpower agreement, announced Friday, as an effort to secure President Bashar Assad’s control and divide rebel factions, the Associated Press reported.
‘‘A rebellious people who have fought and suffered for six years cannot accept half-solutions,’’ said Ali al-Omar, Ahrar al-Sham’s second-in-command said.
But Omar and other rebel leaders stopped short of fully rejecting the interim truce, and many of the opposition groups are expected to respect it temporarily because it will allow them to regroup.
More than 2,000 people have been killed in fighting over the past 40 days in Aleppo, including 700 civilians and 160 children, the AP reported, citing a Syrian human rights group.
One of the goals of the cease-fire agreement is to allow the UN to establish aid corridors into Aleppo.
On Saturday, presumed Russian or government airstrikes on rebel-held Idlib and Aleppo provinces killed more than 90 civilians, including 13 children in an attack on a marketplace in Idlib, according to the Britain-based Syrian Observatory for Human Rights. Airstrikes also hit Douma, a Damascus suburb.
Rebels have no airpower, but they attacked government-held territory, mainly with mortar shells. The Syrian state news media reported rebel shelling in several cities — Damascus, Aleppo, Hama, and Daraa — but did not say whether there were any casualties.
In any war, it is common for the parties to escalate attacks in the days or hours before a truce, and in this case the uptick was sharp.
“I will tell my expectations for the coming two days,’’ Abdelkafi al-Hamdo, a schoolteacher and antigovernment activist, said in a text message minutes after the deal between the United States and Russia was announced.
“Assad will try to kill as much as possible before the claimed cease-fire,’’ he said, referring to the president of Syria. “A lot of shelling and bombs will fall upon civilians, especially the almost empty markets.’’
On Sunday, Hamdo wrote grimly, “We know what Assad and Russia are.’’
Government-controlled news media said Sunday the Syrian armed forces had carried out attacks on insurgents in several provinces. Russian officials have denied that their warplanes have been responsible for a single civilian casualty in nearly a year of airstrikes.
The Syrian government, Iran, and Hezbollah have all declared that they accept the deal.
The heaviest strikes over the weekend happened in Idlib, a province held by insurgents ranging from the former Nusra Front, a group linked to Al Qaeda that recently changed its name to the Levant Conquest Front, to US-backed rebel groups.
The strikes hit a marketplace as people shopped for Eid al-Adha, or the Feast of the Sacrifice, a major Muslim holiday. The cease-fire is set to begin Monday at sundown, when the holiday starts.
“Idlib’s people got a gift for the feast,’’ said Mohammad Najdat Kaddour, a resident of the nearby town of Binnish who came to Idlib to film the aftermath. “This was their gift.’’
“People decided to go out after hearing there was a truce on Eid,’’ he said via internet chat. He said he was incensed not only at the Syrian government but also at the United States for supporting a deal he considered worthless.
“Do you believe there’s something called a truce?’’ he said. “They are all a bunch of criminals.’’
Residents compiled a list of the dead, including three young siblings, Sidra, Abdelkareem, and Mohammad Arafa, who had been killed along with their mother.
Videos from the scene posted online showed piles of rubble and overturned carts, and the bodies of children and adults.
In Douma, near Damascus, residents reported the deaths of two young brothers who had lost a third brother last year.
In Aleppo, doctors reported new casualties Sunday morning from another round of barrel bombing. Youssef Mohamamd Almosto, 60, was reported dead; a 36-year-old man had a leg amputated, and several children were being treated for injuries.
Virtually all Syrians would welcome a respite from fighting and bombing, as was provided under a short-lived cease-fire in February. They therefore might be willing to give it a try, even though the Russian and United States officials who brokered it have themselves voiced their doubts that it will work.
Other opposition groups have been warned that they may also be hit by airstrikes if they do not leave areas where Nusra is present or remove the militant group itself — something not always possible for weaker groups to do without abandoning their home areas.
The plan accepts the presence on the battlefield of other groups designated as terrorists by the United States — such as Hezbollah — that are battling on the side of the Syrian government, and considers them parties to the cease-fire.
