The British ship docked in the southwestern French city of Bordeaux reports 49 suspected cases.

French authorities have temporarily prevented 1,233 passengers and 514 crew from leaving a British cruise ship docked in the southwestern city of Bordeaux after nearly 50 suspected gastroenteritis cases were reported on board.

The vessel, the Ambition, was carrying mostly British or Irish nationals and one French person and had travelled from Belfast and Liverpool before arriving in southwestern France on Tuesday evening.

In a statement on Wednesday, the regional health authority said there was no indication the apparent stomach flu outbreak was linked to a hantavirus cluster reported on the luxury ship MV Hondius, which had travelled between Argentina and the Canary Islands.

Officials said the restriction on disembarkation was a precautionary measure while medical tests were carried out.

Cruise operator Ambassador Cruise Line said enhanced sanitation and prevention measures had been introduced immediately on the vessel.

The company said 48 passengers and one crew member were displaying gastrointestinal symptoms as of Wednesday morning.

Ambassador said its data showed cases had risen after passengers boarded in Liverpool on Saturday. All shore excursions at Bordeaux were cancelled and affected passengers offered full refunds, the company said.

“Once clearance is granted, guests will be permitted to disembark,” the company said in a Facebook post.

Ambassador Cruise Line, a no-fly British operator targeting passengers above the age of 50, was founded in 2021 by Christian Verhounig, the former chief executive of Cruise & Maritime Voyages, which went into administration in 2020.

One 92-year-old British passenger had died on board of cardiac arrest on Monday during a stop in Brest, Brittany, ‌in northwestern France. That death did not appear to be associated with the gastrointestinal outbreak at this stage, the Gironde prefecture said.

Gastrointestinal illnesses are relatively common on cruise ships because viruses can spread quickly in enclosed spaces.

The US Centers for Disease Control and Prevention has reported four outbreaks on cruise ships so far this year, including cases linked to E coli and the norovirus.

Gastroenteritis, often referred to as stomach flu, commonly causes vomiting and diarrhoea. While highly contagious, it is usually not serious although it can sometimes lead to complications such as dehydration.

Health officials stressed that the illness differs significantly from the hantavirus, which has a much higher fatality rate but rarely spreads between people and generally requires close contact for transmission.