Syrian warplanes mounted around a dozen air strikes on the Islamic State-held city of Raqqa on Thursday, activists reported, in an unusually heavy attack by government forces on an area also being targeted by a U.S.-led coalition.
Activist group Raqqa is Being Slaughtered Silently said on its Twitter feed that "regime jets" had mounted more than 12 raids on the city, which is a major base for Islamic State in Syria, and listed eight targets.
"There is news about a large number of martyrs and wounded," it said.
The Syrian Observatory for Human Rights said jets believed to belong to the Syrian military had mounted at least 11 air strikes.