The Islamic State of Iraq and the Levant (ISIL) has retaken the Syrian city of Raqqa after fierce fighting for the northern provincial capital, activists said.
The al-Qaeda-linked group has been battling a coalition of rebel groups of different ideologies in opposition-held areas across northern Syria.
"ISIL took full control of the city of Raqqa after days of clashes," the Syrian Observatory for Human Rights said.
Raqqa is the only provincial capital the rebels have managed to fully prise from government control and subsequently became an ISIL stronghold.
A brigade loyal to the Jabhat al-Nusra, which is also al-Qaeda-linked, has been battling ISIL fighters in Raqqa, even though the group has largely stayed out of the fighting within rebel ranks elsewhere in Syria.
Al-Nusra is recognised by the al-Qaeda leadership as the network's branch in Syria. It recognises ISIL's operational command only in neighbouring Iraq.