Syria barrel bombs 'kill dozens in Islamic State areas'
Syrian planes and helicopters have dropped barrel bombs on Islamic State-held areas in the north-east, killing some 40 people, activists say.
The barrel-bombs, crudely made drums of explosives, were dropped during Thursday and overnight, targeting al-Bab and Qabaseen near Aleppo.
Activists say the government has stepped up air raids in recent days.
Some 200,000 people have been killed since the uprising against President Bashar al-Assad erupted in 2011.
Another 3.2 million people have fled Syria and 7.6 million have been displaced inside the country.
Al-Bab, a city of about 100,000 people, has witnessed heavy government air strikes since September, when a US-led coalition started targeting IS in Iraq and Syria.
One Qabaseen resident, Yousef al-Saadi, told Reuters via Skype: "People were going about scraping a living and there were no armed groups in the market, only poor people. Why is Assad killing us? May God bring vengeance on him."
The UN and rights groups have repeatedly accused Syria of targeting civilian areas.
On Friday, the Combined Joint Task Force said that the US-led coalition had carried out another 31 air strikes on Islamic State targets in Iraq and Syria.
Sixteen of Friday's strikes were in Syria, with 13 of those targeting areas around Kobane on the Turkey border.
The 15 air strikes in Iraq were in seven different areas.
What are barrel bombs?
Barrel bombs are large cylindrical metal containers filled with explosive and shrapnel that are typically rolled out of the door of a helicopter.
The BBC's Defence Correspondent Jonathan Beale says that the bombs were initially dropped from a low altitude, which afforded a reasonable degree of accuracy.
However Syrian government helicopters have been forced to drop them from greater heights because rebel fighters have managed to acquire surface-to-air missiles. This makes the air raids less accurate.
Despite being rudimentary weapons, their destructive power is considerable.
They are only one part of the arsenal that Syria has employed against civilian areas and their use could well constitute a war crime, our correspondent adds.