French television network TV5Monde on Wednesday evening said it had been hacked by individuals claiming to belong to the Islamic State group who had hijacked its TV channels, websites and Facebook page.
"We are no longer able to broadcast any of our channels. Our websites and social media sites are no longer under our control and are all displaying claims of responsibility by Islamic State," the broadcaster's director general Yves Bigot told AFP.
The hackers posted documents on TV5Monde's Facebook page purporting to be the identity cards and CVs of relatives of French soldiers involved in anti-IS operations.
The attack began at around 10:00 pm (2000 GMT), but the global French-language broadcaster appeared to have regained control of its Facebook page by midnight. The network's TV station was still down, however.
"The CyberCaliphate continues its cyberjihad against the enemies of Islamic State," read a message posted by the hackers on TV5Monde's Facebook site.
It also accused French President Francois Hollande of having committed "an unforgivable mistake" by getting involved in "a war that serves no purpose".
France is part of a US-led military coalition carrying out air strikes against IS in Iraq and Syria, where the jihadist group has seized swathes of territory in recent months and declared an Islamic "caliphate".