French policeman assists a blood-covered victim near the Bataclan concert hall following attacks in Paris, France, November 14, 2015. [Photo/Agencies]

CAIRO, Nov 14 - Islamic State claimed responsibility on Saturday for attacks that killed 127 people in Paris, saying it sent fighters strapped with suicide bombing belts and carrying machine guns to various locations in the heart of the capital.

The attacks were designed to show France would remain a top target for the jihadist group as long as the country continued its current policies, the group said in a statement.

Gunmen and bombers killed at least 127 people in Friday's attacks.

Islamic State earlier on Saturday distributed an undated video threatening to attack France if bombings of its fighters continued.

The group's foreign media arm, Al-Hayat Media Centre, made threats through several militants who called on French Muslims to carry out attacks.

"As long as you keep bombing you will not live in peace. You will even fear traveling to the market," said one of the militants, identified as Abu Maryam the Frenchman.

French President Francois Hollande said on Saturday the attacks in Paris were "an act of war" organised from abroad by Islamic State with internal help.

The location of the Islamic State fighters in the video was not clear and it was not possible to determine when it was filmed, but the message was unmistakable.

The militants, who appeared to be French citizens, sat cross-legged in a group wearing fatigues and holding weapons in what appeared to be a wooded area.

The video showed the militants burning passports.

"Indeed you have been ordered to fight the infidel wherever you find him - what are you waiting for? There are weapons and cars available and targets ready to be hit," said Abu Maryam.

Another militant, identified as Abu Salman the Frenchman, said: "Even poison is available, so poison the water and food of at least one of the enemies of Allah."

"Terrorize them and do not allow them to sleep due to fear and horror," he added.

Foreign fighters who join Islamic State, the group which controls large swathes of Iraq and Syria, are seen as especially dangerous because Western passports enable them to live in and travel to Western countries undetected.

"Faced with war, the country must take appropriate action," Hollande said, without saying what that meant.

Hollande said he would address parliament on Monday in an extraordinary meeting and the country would observe three days of official mourning for the victims of Friday's attacks.

Leaders worldwide all condemned the killings in Paris and called for decisive actions.

Chinese President Xi Jinping extended condolences to Hollande on Friday.

In the telegram, Xi said that in this terrible moment for the French people, he would like to condemn, on behalf of the Chinese government and the Chinese people, in the strongest possible terms the barbarism.

He also expressed his grief over those killed in the attacks, and extended condolences to the injured.

China has always been against all forms of terrorism, and is willing to work with France and the international community to strengthen cooperation on security, to combat terrorism and to help protect people in all countries, Xi added.

The Vatican on Saturday condemned the attacks as "mad terrorist violence."

UN Secretary-General Ban Ki-moon said in a statement that he trusts "the French authorities will do all in their power to bring the perpetrators to justice quickly".