Seven children were among a total of 29 people killed Sunday in a series of air attacks on rebel-held areas in the Idlib province in north-western Syria, a monitoring group reported.
The deadliest attack took place in the town of Kafrnabel on the southern edge of Idlib, where unidentified warplanes struck a market place, the Syrian Observatory for Human Rights said.
Footage posted online by activists allegedly from Kafrnabel showed buildings in rubble as ambulances raced to transport the wounded to hospital. Three children were among the 21 dead.
The Observatory said that six other civilians were killed after helicopters dropped barrel bombs in the town of al-Tamana also on the southern outskirts of Idlib.
The dead included four children from the same family.
Airstrikes in the town of Maaret al-Numan and the nearby village of al-Naqir left two women dead, added the Britain-based Observatory, which relies on a network of activists.
Syria's civil war, now in its sixth year, is estimated to have killed more than 300,000 people, mostly civilians.
Idlib is mostly held by a rebel coalition that includes Jabhat Fatah al-Sham, formerly called the al-Nusra Front, a powerful extremist group with ties to al-Qaeda.
Russia, a key military ally of the Syrian government, last month announced the start of a major offensive in Idlib and the central province of Homs.
Moscow said the onslaught was targeting militant groups in both provinces.
Sunday's airstrikes come amid an ongoing government offensive in the rebel enclave in the northern city of Aleppo.
Regime forces and allies are now in control of more than 60 per cent of the opposition section of eastern Aleppo, the Observatory said.
Over 30,000 civilians have fled as a result of government advances since November 24, according to the United Nations.
Eastern Aleppo has been under government siege since July, with medical and food supplies almost exhausted.
Recent regime advances have tightened the siege on the area, local activists said.
