A top restaurant sickened 63 people in Denmark with viral gastroenteritis. The two-star Michelin eatery Noma was ordered to clean up and better food handling.

The Danish Veterinary and Food Administration said Friday it investigated the popular waterfront restaurant in Copenhagen after complaints of customers that had dined there during the same week in February. It was not immediately clear what caused the outbreak.

The virus at the restaurant caused vomiting and diarrhea. Agency spokesman Morten Lisby called the outbreak "massive."

The 63 infected people dinned at Noma between February 12 and 16, according to a food safety report. The inspection involved local restaurants and food retail companies. It also revealed not only illness among customers but those who handled the food.

Restaurant manager Peter Kreiner apologized for the incidents and said working with the officials to track the source of the infection.

"Our business is based on having satisfied customers here and we're incredibly sorry on behalf of our guests," Kreiner told Danish TV2. He said the restaurant had contacted the agency as soon as it became aware of the complaints.

Noma opened in 2004 and is known for its chef, Rene Redzepi. It has hit the top spot three times in the world's best restaurants list in Restaurant magazine. It was credited with the redefinition of Nordic cooking and generally requires reservations months in advance to dine there. They tend to receive thousands of reservation requests every day.