A restaurant in Spain with a Michelin star has reopened almost one month after being linked to the death of a diner and 30 cases of food poisoning.

The Ministry of Health of Valencia detected the cases of food poisoning between Feb. 13 and 16 among customers of RiFF restaurant in Valencia.

More than 100 people who dined at the restaurant between these dates have been interviewed to try and find the vehicle of infection and food samples were sent to the National Toxicology Institute to be analyzed.

Initial investigations and inspections found the restaurant complied with sanitary regulations. It specializes in European cuisine and Mediterranean food. RiFF was opened in September 2001 and achieved a Michelin star in 2009.

Clinical symptoms of most cases were mild and involved vomiting and diarrhea. Spanish media reported a 46-year-old woman died.

In a statement, restaurant owner Bernd H. Knöller expressed his regret at the incident and said he was cooperating with authorities.

Knöller made the decision to close the restaurant until the causes of what happened were established and the Ministry of Health concluded its investigation.

Spanish media reported mushrooms bought from China could be responsible. Responding to these claims, Knöller said mushrooms were bought from an authorized distributor in León and not from China.