Paris is gearing up to hold massive rallies as people are expected to turn up in huge numbers and nearly two dozen world leaders are on their way to condemn the brutal killings over the week.

Amid an enormous security challenge, the French capital will hold a rally at 15:00 on 11 January in honour of the 17 victims of the Islamist attacks.

As many as one million people are to take to the streets to show solidarity against the terror attacks, a day after 700,000 people marched across cities of France.

The French interior minister has said the country will be on high alert for the next few weeks.

French Prime Minister Manuel Valls, addressing a large gathering outside the kosher supermarket, one of the flashpoints of the terror attacks, said: "I have no doubt that millions of citizens will come to express their love of liberty, their love of fraternity. France without Jews is no longer France."

"Journalists were killed because they defended freedom. Policemen were killed because they were protecting you. Jews were killed because they were Jewish. The indignation must be absolute and total not for three days only, but permanently."

"Today, we are all Charlie, we are all police officers, we are all Jews of France."

The dignitaries who will be taking part in the rallies include Israeli Prime Minister Benjamin Netanyahu, British Prime Minster David Cameron, German Chancellor Angela Merkel, Palestinian Authority President Mahmoud Abbas, Russian Foreign Minister Sergei Lavrov and the King and Queen of Jordan. Leaders of Nato and the Arab League are also expected to participate.

Security has been beefed up across the city owing to the fragile situation; hundreds of troops have also been deployed.

"I call on all the French people to rise up this Sunday, together, to defend the values of democracy, freedom and pluralism to which we are attached," said French President Francois Hollande.