French police hunt for Charlie Hebdo accomplice

France's government has urged citzens to remain vigilant as security forces searched for a fourth accomplice in the Charlie Hebdo attack a day after killing the prime suspects in two sieges.

Police and troops on Friday killed brothers Said and Cherif Kouachi after they had taken refuge in a print works in northern Paris, and Amedy Coulibaly after he stormed a kosher supermarket in Porte de Vincennes and killed four people.

The Kouachi brothers were wanted for the Wednesday attack on the satiracal magazine Charlie Hebdo, in which 12 people were murdered. Coulibaly was the suspect in the murder of a policewoman a day after the Hebdo attack.

Police on Saturday said they were searching for Coulibaly's partner, Hayat Boumeddiene, saying they believed she was armed. Christophe Crepin, of the UNSA police union, told the AP news agency that she was considered "the companion of a dangerous terrorist who needs to be questioned".

Boumeddiene (opposite, right), 26, wed Coulibaly (opposite, left) in an Islamic ceremony in July 2009, a union not recognised under French law.

Extra security forces were deployed around the capital on Saturday to guard places of worship and tourist sites, and prepare for a demonstration against extremists on Sunday.

The French interior minister, Bernard Cazeneuve, said the government was deploying hundreds of troops in addition to thousands of police and other security forces and was maintaining its terrorism alert system at the highest level in the Paris region.

He called for "extreme vigilance" from the public, saying that "given the context, we are exposed to risks".

He said police were investigating whether the three dead men were part of a larger network. Five people are in custody as part of the investigation.

The Kouachis were known to authorities: One had a terrorism-related conviction for ties to a network sending fighters to battle US forces in Iraq, and both were on the US no-fly list.

The French radio network, RTL, released audio on Saturday of Coulibaly, in which he attacks Western military campaigns in Syria and Mali, and describes Osama bin Laden as an inspiration.

Al-Qaeda's branch in Yemen said it directed Wednesday's attack against Hebdo to avenge the honor of the Prophet Muhammad, a frequent target of the magazine's satire. The Kouachis were reported to have said that they were working for the Yemen branch as they attacked the office.