An investigation has been opened after a woman died after eating at a Michelin-starred restaurant in Valencia, Spain.

The 46-year-old woman reportedly ate a dish containing morchella fungi (AKA "true morel"), which can be poisonous if not cooked correctly and has a highly poisonous, lookalike cousin known as "false morel."

A total of 18 other diners experienced symptoms of food poisoning that evening.

Regional health authorities are working to determine the cause of death.

The restaurant has been closed down pending the results of the investigation.

A woman died after eating at a Michelin-starred restaurant in Valencia, Spain, Spanish media reported on Wednesday evening.

María Jesús Fernández Calvo, 46, ordered a rice and morchella fungi dish at RiFF restaurant in the city on Saturday, according to The Telegraph.

She later died in her home on Sunday morning after suffering from bouts of vomiting and diarrhoea, Spanish newspaper El País reported.

An investigation has been opened up to determine whether the cause of death was poisoning or asphyxiation from particles of vomit in her lungs.

The victim wasn't the only one to get to sick — her husband, 12-year-old son, and 16 other patrons also experienced symptoms of food poisoning.

RiFF entrance, Valencia, Spain. Google Maps

"We've conducted a primary inspection of the establishment and everything appears to be normal," explained regional health chief Ana Barceló.

"Analytical tests will now be carried out on the food products."

Morchella fungi, also known as true morels, are considered a delicacy by some chefs but can be poisonous if eaten raw.

The Telegraph reported that inspectors may check if "false morels" — morchella's lookalike, highly poisonous cousins — were served accidentally.

Public health officials inspected the restaurant on Monday but did not find any problems that could have contributed to the food poisoning, El País reported.

"We will have to wait for the autopsy to be carried out on the woman before we can determine whether it was the ingestion of a food that directly caused her death, or whether it prompted a state that led to this fatal outcome, or if she had an existing condition," Barceló said.

In a statement sent to INSIDER, RiFF said: "Last week, a number of our guests suffered stomach complaints."

"Public health authorities are currently analyzing the situation to determine the source of these illnesses.

"Tragically, one of the persons affected died at her home on Sunday morning. The cause of her death has not yet been determined.

"We are awaiting the results of the official investigation which will determine whether the cause of death has any connection with the food served at the restaurant. All other guests have recovered from the symptoms.

"On Tuesday Bernd H. Knöller, the owner of the restaurant took the decision to close the restaurant as a precautionary measure until the official investigation is concluded. As soon as these results are made public we hope to reopen with full guarantees to our customers.

"We will keep you informed as soon as we receive the conclusions of the investigation."

The Valencian restaurant opened up in 2001 and achieved a Michelin star in 2009. The Michelin guide calls the restaurant: "A centrally located and meticulously appointed restaurant with a studied minimalist-inspired look."