Montrealers place pencils in front of the French Consulate, in tribute to the victims of the shootings by gunmen at the offices of the satirical weekly newspaper Charlie Hebdo in Paris, in downtown Montreal, January 11, 2015. [Photo/Agencies]

Two of the gunmen had declared allegiance to al Qaeda in Yemen and a third to the militant Islamic State. All three were killed during the police operations in what local commentators have called "France's 9/11", a reference to the September 2001 attacks on US targets by al Qaeda.

Interior Minister Bernard Cazeneuve said that at a meeting in Paris on Sunday European interior ministers had agreed to boost cooperation to thwart further militant attacks.

He called for the creation of a European database of airplane passenger names and said Europe should fight against abusive use of the Internet to spread hate speech.

While there has been widespread solidarity with the victims, there have been dissenting voices.

French social media have carried comments from those uneasy with the "Je suis Charlie" slogan interpreted as freedom of expression at all cost. Others suggest there was hypocrisy in world leaders whose countries have repressive media laws attending the march.

Far-right National Front leader Marine Le Pen, whom analysts see receiving a boost in the polls due to the attacks, said her anti-immigrant party had been excluded from the Paris demonstration and would instead take part in regional marches.

Less than 1,000 people gathered in the National Front-ruled southern town of Beaucaire.