The first French submarine to be launched in a decade, the Suffren is the frontrunner for a new line of Barracuda attack-class vessels, 12 of which have already been ordered by Australia.

A vast, 99-metre (325 foot) behemoth of black steel, the Suffren was launched at a dry-dock ceremony in the northern port of Cherbourg.

Built by French shipbuilder Naval Group for the French navy, the Suffren is a Barracuda-class nuclear attack submarine designed to replace the Rubis-class submarines which have been in service since the 1980s.

The vast billion-euro stealth vessel, whose sides were draped with the French flag, dwarfed a 700-strong crowd of international delegates who looked on as Macron officially launched the Suffren by simply pulling down a lever.

French Defence Minister Florence Parly was there alongside her Australian counterpart Linda Reynolds, whose country inked a deal in February to buy 12 conventionally-powered attack-class submarines from Naval Group.

"With the Suffren, a hunter is born today, not a vessel which is going to hide in the depths of the ocean," Admiral Christophe Prazuck, the French navy's chief of staff, told reporters.

"This is a vessel which has been fashioned to fight... to face down enemies," he said.

The dock where the Suffren is standing will be flooded later this month, then it will be trialled at sea. It will be formally delivered to the French navy at the southern port of Toulon near Marseille by summer 2020.

The SSN's mission is to protect strategic vessels such as aircraft carriers and nuclear-powered submarines which are equipped with ballistic missiles (SSBNs) but also to track enemy vessels and to gather intelligence.

"This puts us in the top division," said Naval Group's chief executive Herve Guillou of the vessel, which took 10 years to develop and build as part of a 9.1-billion-euro programme.

The Barracuda also has other capabilities, including a long-range, 1,000-kilometre strike with a cruise missile, and a mini submarine for special forces which is housed in a dry-deck shelter fitted on the hull.

It can also lay mines.

mra-leb/hmw/sjw/dcr

NAVAL GROUP