Hackers claiming allegiance to the Islamic State group seized control of a French television network, simultaneously hacking 11 channels and the network's website and social media accounts.

The hackers briefly cut transmission of 11 channels belonging to TV5 Monde and took over its websites and social media accounts starting Wednesday night. The channel's director, Yves Bigot, said the attack was continuing Thursday morning. He told RTL radio that the network has restored its signal but can only broadcast recorded programs.

The Islamic extremist group has claimed complex hackings before, but the seizure of the French network appeared to be a new step in its information warfare tactics.

Bigot said he was shaken when he saw the black screen across the network's broadcasts "and 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."

In a Facebook message that went up after the network resumed control of the site, Bigot said the "very powerful cyberattack" began Wednesday at 10 p.m. He later said he hoped the network would be able to regain full control by late Thursday morning.

The message on the TV5 Monde website read in part "I am IS" with a banner by a group that called itself Cybercaliphate. That was replaced later Thursday by a simple message saying that it was undergoing maintenance. A group with the same name hacked Newsweek's Twitter feed in February.

Prime Minister Manuel Valls, on his Twitter account, called the attack "an unacceptable insult to freedom of information and expression" and expressed his support for the editorial staff. Interior Minister Bernard Cazeneuve, Foreign Minister Laurent Fabius and Culture Minister Fleur Pellerin visited the channel's Paris headquarters Thursday.

TV5 Monde, which calls itself the "worldwide French cultural channel," broadcasts programs produced in France, Belgium, Switzerland and Canada, as well as movies, news and other programs. Its Facebook page said its signal reaches more than 257 million homes in over 200 countries and territories.

After January terrorist attacks in France by gunmen claiming links to the Islamic State group and al-Qaida in Yemen, officials said hackers had targeted some 19,000 French websites.