The French government says it will deploy 10,000 extra soldiers to boost security in response to the deadly attacks that rocked the country last week.

On Monday, the government held a crisis meeting with cabinet ministers and police on national security, announcing about 5,000 police would be sent to protect “sensitive” sites and Jewish schools around the country.

Troops would be sent as reinforcements during the next two days.

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“This is the first time that our troops have been mobilised to such an extent on our own soil,” Defence Minister Jean-Yves Le Drian said.

The meeting comes amid questions over how the gunmen – Said Kouachi and his brother Cherif Kouachi – known to the authorities were able to launch the raids in Paris.

The assault on the offices of satirical magazine Charlie Hebdo and separate attacks on police officers and a kosher supermarket killed 17 people.

Authorities are still hunting for possible accomplices of the three gunmen who carried out the three-day killing spree.

Amedy Coulibaly, who killed a policewoman in southern Paris then four Jewish shoppers in a hostage drama, probably received help from someone else, French Prime Minister Manuel Valls said, pledging “the hunt will go on”.

More than 1.5 million people marched in Paris on Sunday in a show of unity.

The French press hailed Sunday’s rallies, with all major newspapers splashing photos of the sea of humanity on the French capital’s streets.

Banner headlines read “A people rise up”, “Freedom on the march,” and “France stands up”.

Meanwhile, Turkey’s foreign minister says the common-law wife of the man behind the attack on a French kosher supermarket last week crossed into Syria from Turkey on January 8.

Mevlut Cavusoglu told the state-run Anadolu Agency on Monday that Hayat Boumeddiene arrived in Turkey from Madrid on January 2, ahead of the attacks and stayed at a hotel in Istanbul.

He said Turkish authorities established that she had crossed into Syria on Thursday, the day her husband shot a policewoman to death on the outskirts of Paris and a day after the Charlie Hebdo massacre.

– with AAP