French television network TV5Monde was forced to broadcast only pre-recorded programmes Thursday after it was hacked by individuals claiming to belong to the Islamic State group, who also hijacked its websites and social networks.

The Paris-based company was able to partially resume television broadcasts by 1 am (2300 GMT) after a three-hour blackout, the network's director-general Yves Bigot told AFP, but added its systems had been "severely damaged" by an "unprecedented attack".

"We can only broadcast pre-recorded programmes. We are not yet in a position to re-establish our broadcasting schedule nor to produce programmes," Bigot said early Thursday on RTL radio.

"When you work in television... and you find out that your 11 channels are down, of course that's one of the most dreadful things that can happen to you," added Bigot.

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, along with threats against the troops.

"Soldiers of France, stay away from the Islamic State! You have the chance to save your families, take advantage of it," read one message on TV5Monde's Facebook page. "The CyberCaliphate continues its cyberjihad against the enemies of Islamic State," the message added.

TV5Monde regained control of its social networks by 2:00 am Thursday but television broadcasts were likely to take hours, if not days, to return to normal. The attack would have required weeks of preparation, Bigot added.

Bigot told AFP earlier in the evening: "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."

Its website were still offline by 9:00 am, displaying an "under maintenance" message to visitors.

- 'Unacceptable attack' -

Prime Minister Manuel Valls said the hack was an "unacceptable attack on the freedom of information and expression", voicing "total solidarity with the editorial staff."

The hackers had accused French President Francois Hollande of committing "an unforgivable mistake" by getting involved in "a war that serves no purpose".

"That's why the French received the gifts of Charlie Hebdo and Hyper Cacher in January," it said on the broadcaster's Facebook page, referring to the twin attacks by Islamist gunmen in Paris that left 17 people dead over three days and deeply shocked France.

Jihadists have become increasingly adept at using the Internet to spread propaganda and attack media outlets.

In Feburary, the Twitter feed of Newsweek was briefly hacked and threats were made against President Barack Obama's family.

And in the immediate aftermath of the Charlie Hebdo attacks, hackers claiming to be Islamists hijacked hundreds of French websites, flooding them with jihadist propaganda.

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 and declared an Islamic "caliphate".

More than 1,500 French nationals have left France to join the militants' ranks in Iraq and Syria, where they represent almost half the number of European fighters present, according to a report released Wednesday by the French Senate.

TV5Monde is broadcast in more than 200 countries worldwide.

White House will not name those behind 2014 cyber attack
Washington (AFP) April 8, 2015 - The White House said Wednesday it would not name those behind a cyber attack on official Washington targets last October, after reports blamed Russia.

"Our investigators have concluded that it's not in our best interest to identify the entity that may be responsible for this specific activity of concern," White House spokesman Josh Earnest said.

Asked why the administration was refusing to disclose who was behind the hack when Washington accused North Korea of attacking Sony last year, Earnest said in that case the FBI determined it could be "more effective" to hold the North Koreans accountable for the cyber vandalism.

Earnest said the attack last fall appeared not to have compromised the White House's classified network.

"But there were some elements of the system that were affected when our computer administrators took steps to mitigate the impact of the activity of concern. Much of that capability has been restored," he said.

CNN earlier reported that Russia was behind the October attack, which originated at the State Department, but was confirmed to have hit the White House too.