In a show of unity, about 40 world leaders joined the start of the march which is considered to be one of largest demonstrations the
country has seen in recent times.

Hollande said "Paris is today the capital of the world."

He said the entire country will rise up and show its best side.

UK PM David Cameron Cameron tweeted: "I've just arrived at the Élysée to meet President Hollande. We'll March together for our values and those murdered at #CharlieHebdo."

The relatives of the victims of last week's attacks led the rally which started from the Place de la Republique.

An estimated 1.3 million to two million people participated in the rally, where marchers were seen holding flags of different countries,
to pay tribute to the victims.

 Leaders from Germany, Italy, Israel, Turkey, Britain were seen walking along with the common people as the country is still reeling
from the shock of the slayings of innocent people, including cartoonists, last week.

"World leaders, including British Prime Minister David Cameron, German Chancellor Angela Merkel, Turkish Prime Minister Ahmet Davutoglu, Israeli Prime Minister Benjamin Netanyahu and Palestinian President Mahmoud Abbas joined the beginning of the  Paris  march," BBC reported.

Security was beefed up across the country with about  2,200 police and soldiers  seen patrolling the streets of Paris to protect the
marchers.

Marchers in Paris were heard chanting "liberte" ("freedom") and "Charlie".

Earlier, Prime Minister Manuel Valls said France is now at war with radical Islam.

“It is a war against terrorism, against jihadism, against radical Islam, against everything that is aimed at breaking fraternity, freedom, solidarity,”  Valls said in a speech.

France witnessed a dark day in its history on Jan 7 with gunmen attacking the Paris office of French satirical magazine Charlie Hebdo
and killing at least 12 people , including cartoonists and two policemen, as global leaders joined to condemn the incident.

The militants suspected of orchestrating France’s worst terror onslaught - two brothers of Algerian descent and an associate of  African origins - were killed.

Also dead were four of the people held hostage at Hyper Cacher, the kosher supermarket located in eastern Paris.

Altogether, 20 people, including the three militants, died in three days of bloodshed.

President Francois Hollande, in a solemn address to the nation on Friday, described as the work of “madmen, fanatics” who had created “a tragedy for the nation that we were obliged to confront.”

Meanwhile, a video has emerged which showed the supermarket attacker, Amedy Coulibaly, pledging allegiance to the so-called militant group Islamic State.