Scores of people have been killed in a two-day assault by the Syrian army on a northern rebel-held town near the city of Aleppo.
Helicopters bombarded al-Bab on Sunday, killing at least 30 people including four women when they dropped improvised 'barrel bombs' on a market district, sources in the town told Al Jazeera.
|Four women were among the dead in Sunday's attack [Al-Bab Coordination Committee/Al Jazeera]
Activists said that the death toll could rise because many people were severely wounded in the raid.
The attack came a day after 27 people were reported killed in a similar attack on the same town by President Bashar al-Assad's forces.
A barrel bomb - explosives-filled cylinders or oil barrels - was rolled out of the back off a helicopter and exploded in a residential area, a video uploaded to youtube on Sunday appeared to show.
A voice in the video describes the object as an "explosive barrel" and it sends plumes of grey smoke rising up over the skyline.
Other videos uploaded to the Internet appeared to show piles of rubble from crushed buildings, blazing fires and a dusty-haired child carrying a baby and walking away from what appeared to be a blast site.
The bombardment of al-Bab, around 40 km north east of the divided city of Aleppo, follows gains by Assad's forces on Aleppo's south east approaches last month and could herald a similar ground offensive in the area.
“It seems that the regime is determined to hit the supply route [of rebels] between al-Bab and the city of Aleppo,” Barry Abdul Latif, an activist in al-Bab told Al Jazeera.
“But the shelling of the regime is only targeting heavily populated civilian neighbourhoods and away from any rebel headquarters,” he added.
The offensive on al-Bab comes at a time of heavy fighting across the country, particularly around Aleppo, in the Qalamoun region, which overlooks the main highway north from Damascus and the eastern suburbs of the capital.
Since rebels threatened Damascus late last year, Assad has been consolidating his military power around the capital and in the centre of the country.
His forces have been trying to push rebels out of Nabak, which lies on the Damascus-Homs road.