French international channel TV5Monde was hacked by Islamic State (IS) jehadis, the channel said.
"The web site and antennas of TV5Monde are suffering from an extremely powerful cyber attack. Our team is working on it," the public broadcaster wrote on its Twitter account late Wednesday.
The channel's director general, Yves Bigot, said they had stopped broadcasting and suspended all normal operations, Spanish news agency Efe reported.
The attackers are alleged to have released personal information of military personnel on French aircraft carrier Charles de Gaulle, used to bomb the IS in Iraq.
A jehadi post on TV5Monde's Facebook page warned: "Soldiers of France stay away from the Islamic State! You have the chance to save your families, take advantage of it."
It threatened French President Francois Hollande for sending troops to fight thet IS. It also threatened action against the families of French soldiers.
Digital director of TV5Monde Helene Zemmour said it would be difficult to resolve the situation as hackers had attacked the internal system of the channel.
TV5Monde, founded in 1984, is headquartered in Paris. It reaches more than 257 million households in over 200 countries.