Hundreds of employees of the French aerospace group Airbus Atlantic fell ill with gastroenteritis after a Christmas meal attended by 2,600 employees, reports The Guardian.

Health authorities have launched an investigation to determine what caused the illness of 700 employees.

The celebratory meal was organized and provided by the company’s restaurant in Montoire-de-Bretagne, in the Loire-Atlantique region of western France.

The menu included foie gras, scallops, lobster and tournedos, followed by desserts such as ice cream and hazelnut and chocolate mousse for just €15 per person.

The affected employees developed “vomiting and/or diarrhea” after the holiday dinner on December 14.

Most were sick within 24-48 hours after eating.

Health officials said they have not yet determined the cause of the mass illness and are investigating whether it was caused by food-borne bacteria or highly contagious viral gastroenteritis.

One employee said it was “worse than if I had given birth” when she described the pain she felt.

Jean-Claude Iribarren, a spokesman for Airbus Atlantic, said the food was prepared by the company’s canteen. “As we do every year, we are hosting a Christmas dinner for 2,600 people with many local suppliers,” he said.

“People were a bit hasty about the reasons. We are required to keep samples of every product served in the restaurant. They will be analyzed by ARS [autoritățile sanitare]. The investigation will continue for several more days.”

An Airbus spokesman said no one was “seriously ill”. “Now the case is handled by the health protection authority, which is conducting an investigation.”

Airbus Atlantic, a subsidiary of the world’s largest aircraft manufacturer Airbus, has 15,000 employees in five countries.