French President Francois Hollande is surrounded by heads of state including Germany's Chancellor Angela Merkel, and Italy's Prime Minister Matteo Renzi as they attend the solidarity march (Marche Republicaine) in the streets of Paris January 11, 2015. [Photo/Agencies]

PARIS - World leaders including Muslim and Jewish statesmen linked arms to lead more than a million French citizens through Paris in an unprecedented march to pay tribute to victims of Islamist militant attacks.

At least 3.7 million people demonstrated in France on Sunday, the Interior Ministry said.

A ministry spokesman said that 1.2 million to 1.6 million people had marched in Paris and about 2.5 million people in other cities around the country.

The ministry said it was the biggest popular demonstration ever registered in the country.

Commentators said the last time crowds of this size filled the streets of the capital was at the Liberation of Paris from Nazi Germany in 1944.

President Francois Hollande and leaders from Germany, Italy, Turkey, Britain as well as Israel and the Palestinian territories moved off from the central Place de la Republique ahead of a sea of French and other flags.

Seventeen people, including journalists and police, were killed in three days of violence that began on Wednesday with a shooting attack on the political weekly Charlie Hebdo, known for its satirical attacks on Islam and other religions.

Giant letters attached to a statue in the square spelt out the word "Pourquoi?" (Why?) and small groups sang the "La Marseillaise" national anthem.

"Paris is today the capital of the world. Our entire country will rise up and show its best side," Hollande said.