France remains on high security alert, Interior Minister Bernard Cazeneuve said after a Saturday morning meeting at the Elysee Palace, as police continued searching for a female suspect linked to the Paris attackers.

Two brothers suspected in the attack on the French satirical magazine Charlie Hebdo, and a third man accused of killing a policewoman, were shot dead by police after taking hostages Friday in and near Paris.

Hayat Boumeddiene, 26, the alleged companion of Amedy Coulibaly - who took hostages at a kosher supermarket in Paris - was still at large. Police said she could be "armed and dangerous."

Coulibaly, 32, shot dead four hostages when he stormed the Jewish store, before being killed in a shootout with police hours later, federal prosecutor Francois Molins said.

Coulibaly told BFMTV broadcaster that he had coordinated with brothers Cherif, 32, and Said Kouachi, 34, who police say carried out Wednesday's attack on Charlie Hebdo, in which 12 were killed.

He added that he was sent by radical jihadist group the Islamic State, while Cherif Kouachi told BFMTV before being killed by police that he was sent by al-Qaeda in Yemen. Cherif had travelled to the Middle Eastern country in 2011, according to Molins.

Boumeddiene allegedly married Coulibaly in a religious ceremony that was not registered with civil authorities. According to Molins, more than 500 phone calls were exchanged between her phone and that of Cherif Kouachi's wife, Izzana Hamyd.

Photos from 2010 show Boumeddiene posing in a niqab with a crossbow, alongside Coulibaly.

Five other people remain in custody in connection with this week's events, according to the prosecutor. Their identity has not been disclosed.

On Friday, Prime Minister Manuel Valls said the country was facing an "unprecedented terrorist challenge," adding there were security inadequacies leading up to the attack.

"There was obviously a flaw," he said in a televised interview. "When there are 17 deaths, then there have been failures."

After the security meeting at the Elysee with top ministers and President Francois Hollande, Cazeneuve said at least 320 additional forces would be deployed and vigilance would remain high - particularly at places of worship.

He added that plans were under way for increased security measures at a planned march on Sunday to honour the victims of the attack and bolster social unity.

A number of European leaders are expected to attend, including German Chancellor Angela Merkel, British Prime Minister David Cameron, Italian Prime Minister Matteo Renzi and Spanish Prime Minister Mariano Rajoy. Turkish premier Davutoglu added himself to the list on Saturday, according to French news agency AFP.

Al Qaeda threatens new attacks

Meanwhile, the Yemen-based al-Qaeda in the Arabian Peninsula (AQAP) has threatened France with more attacks if it does not stop fighting Islam and its symbols.

Top AQAP cleric Harith al-Nadhari praised the slain assailants in France, saying in an audio message broadcast on the pro-AQAP online broadcaster al-Malahem they were "soldiers who do not fear death."

"Some of the sons of France were disrespectful to the prophets of Allah, so a group from among the believing soldiers of Allah marched unto them, then they taught them respect and the limit of the freedom of expression," al-Nadhari said.

A cleric from the Sunni extremist militia Islamic State on Friday also claimed that the group was responsible for the Charlie Hebdo attack.

"We started with the France operation for which we take responsibility. Tomorrow will be in Britain, America and others," Abu Saad al-Ansari said in a sermon in the Islamic State-controlled Iraqi city of Mosul.

Charlie Hebdo was known for his caricatures of the Prophet Mohammed, among other religious and institutional targets.

- dpa