France calls on EU states to aid war on IS

France has called on members of the EU to aid its military operations against the Islamic State group, invoking for the first time an article of the Lisbon Treaty on mutual defence.

French Defence Minister Jean-Yves Le Drian on Tuesday asked other EU states for aid under article 42 of the treaty, which obliges signatories to provide military aid and assistance "by all the means in their power" to any member attacked on its territory.

"France cannot act alone in these theatres," Le Drian told EU defence ministers in Brussels, before later adding that aid could be given "either by taking part in France's operations in Syria or Iraq, or by easing the load or providing support for France in other operations". 

EU defence ministers unanimously backed the request, EU foreign policy chief Federica Mogherini said.

In the UK, Prime Minister David Cameron told MPs that Britain should attack the "head of the snake" and vowed to make the case for bombing in Syria. MPs in 2013 voted against military action in Syria, preventing UK forces from operating there.

France has stepped up air strikes on Islamic State fighters in Syria after the gun and bomb attacks in Paris that killed at least 129 people.

Thousands of soldiers and paramilitary police have been deployed on the streets of the French capital in the aftermath.

France has singled out a Belgian of Moroccan origin, Abdelhamid Abaooud, as being the mastermind of the attacks. He is believed to be living in Raqqa, Syria.

The Lisbon Treaty article used by France is similar to Nato's article five, which the US activated after the 11 September 2001 attacks and triggered the invasion of Afghanistan.

Meanwhile, two people have reportedly been arrested in Belgium on suspicion of making the explosives used in Paris, and for driving fugitive Salah Abdeslam out of the city after the attacks.

La Derniere Heure newspaper said the men were Belgian nationals of Moroccan origin, and named them as Hamza Attou and Mohamed Amri.

Abdeslam, 26, is wanted for allegedly driving three attackers to the Bataclan concert venue, where they killed at least 89 people. The car they used, a rental Polo registered under Abdelslam's name, was abandoned at the site.

He was the subject of police raids in the Molenbeek area of Brussels on Monday, where he was based before the Paris attacks, but is still at large.

Austrian authorities on Tuesday said Abdeslam travelled to Austria in September, telling police after arriving from Germany with two men that he was "on holiday".

The two other men "have so far not been named in connection" with the Paris attacks, the ministry said in a statement.

"Investigations are currently ongoing regarding where the suspect spent time in Austria and the purpose of his stay," it said.

Abdeslam's brother, Brahim, was one of the Paris attackers, blowing himself up near a cafe on the Boulevard Voltaire.