A man lays flowers outside the French embassy in Berlin, Germany, November 14, 2015, after gunmen and bombers attacked restaurants, a concert hall and a sports stadium at locations across Paris on Friday. Photo by Hannibal Hanschke, Reuters.

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

The attacks, described by France's president as an act of war, were designed to show the country would remain in danger as long as it continued its current policies, Islamic State said in a statement.

"To teach France, and all nations following its path, that they will remain at the top of Islamic State's list of targets, and that the smell of death won't leave their noses as long as they partake in their crusader campaign," said the group.

French President Francois Hollande said the violence was organized from abroad by Islamic State with internal help.

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

The attacks at a stadium, concert hall and cafes and restaurants in northern and eastern Paris were "an act of war committed by Daesh that was prepared, organised and planned from outside (of France)" with help from inside France, Hollande said, using the Arabic acronym for Islamic State.

Earlier on Saturday, Islamic State 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.

Hollande said the attacks were "an act of war".

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 fighters, 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?," said Abu Maryam.

"Know that jihad in this time is obligatory on all."

Another militant, identified as Abu Salman the Frenchman, said: "There are weapons and cars available and targets ready to be hit. 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.

Another militant in the video, identified as Abu Osama the Frenchman, appealed to Muslims living in France to head to Syria to wage jihad, in "a message from your French brothers".

"Jihad is the path of Allah You strengthen their economy and pay taxes which they use to fight us, and kill our sister, our women and our children," he said.

"Are you not embarrassed? Repent to your Lord and come join us. Because a day may come when the borders will be closed and you will be left only with tears and regret."