Bombing runs by the Syrian air force over the past 10 days have killed at least 221 civilians, a third of them children, a group monitoring Syria’s civil war said on Thursday.

The intensifying offensive by President Bashar al-Assad’s forces has heightened concerns among his opponents that he may be taking advantage of U.S.-led air raids on Islamic State insurgents to regain territory elsewhere in the country.

Since Oct. 20 the Syrian military has staged at least 769 attacks including barrel bombings in many areas of Syria, according to the Britain-based Syrian Observatory for Human Rights, and more than 500 people have been wounded. […]