At least 43 people were killed on Sunday in air strikes carried out by suspected Russian warplanes in the rebel-held city of Idlib in northwestern Syria.
A further 150 people were wounded after at least six strikes hit a busy marketplace in the heart of Idlib, as well as several government buildings and residential areas, according to Reuters news agency.
Rescue workers confirmed 43 dead, adding at least 30 more bodies had been retrieved that had still to be identified.
"There are a lot of corpses under the rubble," Yasser Hammo, a civil defence worker, told Reuters via an internet messaging system, adding volunteers and civil defence workers were still pulling bodies out.
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The UK-based Syrian Observatory for Human Rights also reported the air strikes, saying at least 36 people were killed.
"The raids, probably Russian, targeted former regime positions now held by the Army of Conquest," observatory chief Rami Abdel Rahman was quoted as saying by AFP news agency.
"Dozens of people, mostly civilians, were wounded" in the raids, Abdel Rahman added.
Khan Tuman seizure
Elsewhere in Syria, pro-regime forces on Sunday seized a strategic rebel stronghold in the northern province of Aleppo, Syrian state media and the observatory reported.
"The army and loyalist forces now control Khan Tuman and surrounding farms in Aleppo province," the official SANA news agency reported.
State television also reported the news, saying: "Khan Tuman and the farms near it are the most important bastion of the terrorist organisations in southwest Aleppo province."
Khan Tuman was the scene of fierce clashes between loyalist forces and rebels, said the observatory.
Abdel Rahman said the battle for the key site saw "heavy bombardments and at least 40 raids by Syrian and Russian warplanes on the region".
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Also on Sunday, a Syrian army bus carrying soldiers was hit by a large explosion in the Mezzeh district in western Damascus, residents told Al Jazeera.
The blast, which went off near the literature department of the Damascus university, wounded at least 10 people, according to Syrian state television.
On Friday, the UN Security Council unanimously agreed on the text of a draft resolution for peace talks in January and a ceasefire aimed at ending the nearly five-year-old civil war in Syria.
John Kerry, US secretary of state, said the resolution aims to install a transitional government within the first six months, paving the way for elections within the next 18 months.
He said any agreement would exclude the Islamic State of Iraq and the Levant (ISIL) and al-Nusra Front.
The text, however, does not mention President Bashar al-Assad's fate or which opposition groups will be included in peace talks.
Source: Al Jazeera and agencies