Hackers claiming allegiance to the Islamic State of Iraq and the Levant (Isil) on Thursday seized control of TV5Monde, France's international TV network, knocking out its 11 channels, website and social media accounts in an attack the government dubbed an "act of terrorism".

TV5Monde was still struggling to regain control of its channels on Thursday morning, forced to broadcast only pre-recorded programmes after what its director called an "unprecedented attack in the history of television" in which its systems were "severely damaged". It was back to normal operations by 8pm on Thursday night.

Yves Bigot, the network's chief, said he was shaken when a black screen appeared across the entire network at around 10pm local time on Wednesday night.

"When we discovered the sense of the message appearing on our social media and our websites, it both allowed us to understand what was happening and obviously worried us," he told RTL radio.