One person has died and eight people have been hospitalized after an outbreak of botulism in a restaurant in the French city of Bordeaux, according to a statement from France's public health body on Wednesday.

Two less serious cases were also identified, according to local health authorities.

It is thought that the diners ate sardines in a home-made oil preserve, which was contaminated with botulism bacteria. They all dined at the Tchin Tchin wine bar from September 4 to September 10, Public Health France said.

According to CNN affiliate BFMTV, the customer who died was a woman in her thirties who was visiting Bordeaux with her partner, who is still in intensive care.

Botulism is a paralyzing nerve toxin, considered to be one of the most potent and lethal substances in the world.

It's produced by the bacterium Clostridium botulinum and sometimes by strains of Clostridium butyricum and Clostridium baratii. The rod-shaped bacteria are commonly found in soil and sediments from lakes, rivers and oceans.

The bacteria thrive in low-oxygen conditions, such as canned foods, deep wounds and the intestinal tract, but when threatened form protective spores with a hard coating that allows the bacteria to survive for years.

Thierry Touzet, deputy director of the Gironde civil protection authority, told journalists Wednesday that the restaurant will be closed for "the next few days, if not weeks" following discussions with the owner to facilitate cleaning and disinfection of the premises.

"He has considered closing for a longer period to carry out all these operations, and also to train in food preservation techniques," Touzet said.

"The establishment was generally well kept however there was a real problem in the process of preserving food," he said, adding that the owner has been asked to no longer make preserved fish.

He added that there were nine jars of the sardines that were served during the week when the infections were identified, and about 25 people may have eaten the fish.

France's public health agency has warned anyone who visited the restaurant and has shown any symptoms of botulism to immediately seek medical help. These symptoms can include abdominal pains, vomiting, diarrhea, blurred or double vision and a dry mouth accompanied by a difficulty swallowing or even speaking.

Treatment of severe botulism infections can involve assisted breathing in intensive care. However, a rapid treatment of antitoxins after the onset of symptoms can shorten hospitalization periods.

Botulism can be fatal in 5-10% of cases, according to Public Health France.

Bordeaux, in southwest France, is known for its history and wine. The city is popular with tourists and is also hosting matches of the ongoing Rugby World Cup.

CNN has reached out to the Bordeaux prosecutor and Tchin Tchin wine bar for comment.