The Olympic flame arrives in France on board a historic masted ship on Wednesday for a ceremony in front of 150,000 people that will be a first major test for organisers and security forces ahead of the 2024 Paris Games.

The transfer of the flame onshore in the southern port of Marseille will mark the start of a 12,000-kilometre (7,500-mile) torch relay across France and its far-flung overseas territories.

Under blue skies and in calm seas the Belem, the 19th-century ship carrying the torch, paraded around the bay of Marseille with hundreds of other boats after appearing on the horizon early Wednesday at the end of its journey from Greece.

The flame will come ashore at 7:45pm (1745 GMT) from the Belem that has made a 12-day trip from Greece, where the flame was lit in Olympia on April 16.

Organisers are hoping the first public spectacle of the Games on French soil -- just 79 days from the opening ceremony -- will help build excitement after a row about ticket prices and concerns about security.

"It's something we've been waiting for for a very long time," chief organiser Tony Estanguet said on Monday, referring to the 100 years since Paris last staged the Games. "The Games are coming home."

France, which was also the host in 1900, sees itself at the heart of the modern Olympic movement after a French aristocrat, Pierre de Coubertin, revived the idea of the Games as practised by the Greeks until the 4th century BC.

After the Covid-hit edition in Tokyo in 2021 and the corruption-tainted Rio de Janeiro Games in 2016, the Paris Olympics are seen as an important moment for the sporting extravaganza.

- 'Unprecedented' -

Organisers expect around 150,000 people to watch the flame's arrival in the Marseille marina, which will host the sailing events during the Olympics.

Fireworks and a free concert will complete the show which will be broadcast live on French TV.

In the background, around 6,000 security forces are on duty at a time when the country is on its highest terror alert.

"It's completely unprecedented for the national police to mobilise so many people on the same day at the same place," regional police coordinator Cedric Esson told reporters on Monday.

The honour of being the first torch bearer falls to four-time Olympic medal-winning swimmer Florent Manaudou.

Other stars to take part in the parade, which continues in Marseille on Thursday, include NBA-winning basketball player Tony Parker and Ivory Coast football great Didier Drogba.

One beach-cleaning charity has boycotted the ceremony to protest against Olympics sponsor Coca-Cola, while there is no scheduled role for Marseille's most famous sporting son, football legend Zinedine Zidane.

- Opening ceremony -

Extremely tight security will be a constant feature as the torch travels through more than 450 French towns and cities, and passes by dozens of tourist attractions including the Mont Saint Michel.

Around 200 members of the security forces are set to be positioned permanently around it, including an anti-terror SWAT team and anti-drone operatives.

Interior Minister Gerald Darmanin has referred to the risk of protests, including from far-left groups or environmental activists such as Extinction Rebellion.

Organisers have promised a "spectacular" and "iconic" Olympics, with much of the sport set to take place in temporary venues around the City of Light including at the Eiffel Tower and the Invalides.

In the absence of a much-feared security scare, the opening ceremony will take place in boats on the river Seine in a radical departure from past Games which have opened in the main stadium.

All of the major infrastructure has been completed with only two new permanent sporting venues built in a bid to reduce the financial cost and carbon emissions of the global extravaganza.

The idea of the torch rally harks back to the ancient Olympics when a sacred flame burned throughout the Games.

The Paris Olympics will run from July 26-August 11, followed by the Paralympics from August 28-September 8.