President Francois Hollande led tributes to the French Resistance on Monday, as Paris celebrated the 70th anniversary of its joyful liberation after four long and bitter years of Nazi occupation in World War II.

Soaked by a torrential downpour on the Ile de Sein off northwestern France, Hollande hailed the bravery of the tiny island's population, who refused to accept their country's occupation and fled to Britain to join the fight for France's liberation.

"A tiny parcel of land in the ocean, the Ile de Sein was in the vanguard, an example, an illustration of French patriotism," he said.

"The message from Ile de Sein is that there is no danger, no difficulty we cannot overcome as long as the will is there, as long as people gather together," said Hollande, who made no reference to his own political difficulties only hours after his prime minister handed in his government's resignation.

Hollande's speech on the island kicked off a day of celebrations that will climax with Parisians marking their city's liberation just as their parents and grandparents did seven decades ago -- with a gala dance at City Hall.

There will also be an altogether more modern twist to the ball later Monday, with a sound and light show and huge projections of previously unseen photos on the facade of the imposing building in central Paris.

The liberation of Paris, which came nearly three months after the D-Day landings began to free Europe from Nazism, started in mid-August in classic French fashion: with a five-day general strike.

The uprising began in earnest on August 19 when up to 3,000 police officers retook their old headquarters and hoisted the French flag, starting a domino effect that would see a succession of public buildings fall into the hands of the French Resistance.

The Nazi military governor of Paris, General Dietrich von Choltitz, negotiated a shaky truce with the Resistance that failed to hold, but famously disobeyed Hitler's orders to destroy the capital's monuments and bridges.

On August 25, as Allied troops flooded into the city, von Choltitz signed his capitulation at Gare Montparnasse.

The losses were minimal for an operation of its size. The French second armored division lost 156 men, the American fourth division none at all. Around 1,000 Resistance fighters died, including 175 police officers.

Historians put German losses at around 3,200.

As spontaneous displays of joy erupted throughout the city with Parisians rushing out to hold impromptu street parties with their liberators, French wartime chief Charles De Gaulle gave a famous speech at City Hall.

"Paris! Paris outraged! Paris broken! Paris martyred! But Paris liberated! Liberated by itself. Liberated by its people," De Gaulle told a swaying mass of rapturous citizens.

The next day, he would march down the Champs Elysees cheered on by a million people.

The celebrations cap a series of events marking the historic battles of 70 years ago, honoring veterans that, many now in their 90s, are unlikely to see many more anniversaries.

World leaders gathered in Normandy in June to mark the 70th anniversary of D-Day, and earlier this month, African heads of state gathered in southeastern France to celebrate the southern landings in France that pushed the Nazis back towards Germany.