The Islamic State has ordered an evacuation from its de facto capital Raqqa following warnings that a dam could collapse, Syrian activists said.

Operation Euphrates Wrath aims to surround and capture Raqqa, the de facto capital of the IS extremists’ self-declared caliphate.

France has launched new air strikes on the so-called 'Islamic State' group's stronghold of Raqqa in Syria, days after deadly attacks in Paris linked to the group.