World leaders in attendance

German Chancellor Angela Merkel, British Prime Minister David Cameron and Italy Prime Minister Matteo Renzi were among 44 foreign leaders marching with Hollande.

U.N. Secretary-General Ban Ki-moon, Israel's Benjamin Netanyahu - who earlier encouraged French Jews to emigrate to Israel - and Palestinian President Mahmoud Abbas were also present.

Immediately to Hollande's left, walked Merkel and to his right Malian President Ibrahim Boubacar Keita. France has provided troops to help fight Islamist rebels there.

In a rare public display of emotion by two major-power leaders, cameras showed Hollande embracing Merkel, her eyes shut and forehead resting on his cheek, on the steps of the Elysee before they headed off to march.

After world leaders left the march, Hollande stayed to greet survivors of the Charlie Hebdo attack and their families. 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.

The official estimate on attendance is due to be announced later. A 1995 protest against planned welfare cuts brought some 500,000-800,000 people onto the streets of the capital, while a 2002 rally against the far-right National Front's then leader Jean-Marie Le Pen afer he got into the run-off of that year's presidential election drew 400,000-600,000.

Twelve people were killed in Wednesday's initial attack on Charlie Hebdo, a journal know for satirising religions and politicians. The attackers, two French-born brothers of Algerian origin, singled out the weekly for its publication of cartoons depicting and ridiculing the Prophet Mohammad (PBUH).

All three gunmen were killed in what local commentators have called “France's 9/11”, a reference to the September 2001 attacks on U.S. targets by al Qaeda.

The head of France's 550,000-strong Jewish community, Roger Cukierman, the largest in Europe, said Hollande had promised that Jewish schools and synagogues would have extra protection, by the army if necessary, after the killings.

France's Agence Juive, which tracks Jewish emigration, estimates more than 5,000 Jews left France for Israel in 2014, up from 3,300 in 2013, itself a 73 per cent increase on 2012.

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.

In Germany, a rally against racism and xenophobia on Saturday drew tens of thousands of people in the eastern German city of Dresden, which has become the centre of anti-immigration protests organised by a new grassroots movement called PEGIDA.

A building of the newspaper Hamburger Morgenpost, which like many other publications has reprinted Charlie Hebdo cartoons, was the target of an arson attack and two suspects were arrested, police said on Sunday.

Turkish and French sources said a woman hunted by French police as a suspect in the attacks had left France several days before the killings and is believed to be in Syria.

French police had launched in an intensive search for Hayat Boumeddiene, the 26-year-old partner of one of the attackers, describing her as “armed and dangerous”.