Earlier, authorities had ordered a lockdown for the more than 1,700 passengers and crew on the vessel, but insisted there was no connection with the hantavirus outbreak suspected of killing three people on the Dutch-flagged MV Hondius cruise ship, which has sparked international alarm.
Testing confirmed the outbreak on the Ambition, a cruise ship anchored in the port of Bordeaux in western France, was "a gastro-intestinal infection of viral origin", the local government and regional health agency said in a statement.
They said there were no severe cases, and that asymptomatic individuals were now free to disembark, but that those infected were required to remain in isolation on board.
News that a 92-year-old British passenger had died on the ship as dozens of others suffered upset stomachs initially caused concern.
But health authorities said the man had suffered a heart attack and that his death appeared unrelated to the illnesses.
