The National Environment Agency (NEA) on Monday downgraded the Summer Palace restaurant and the banquet kitchen of Regent Singapore to "C" following multiple cases of food poisoning involving the two food establishments last year.
A total of 43 people who ate food from the establishments on November 11 had stomach flu - or gastroenteritis - symptoms, NEA said in an advisory.
NEA will review the grades in 12 months, and will keep the premises under surveillance in the meantime.
Michelin one-star Cantonese restaurant Summer Palace and the five-star hotel's banquet kitchen previously had "A" grades for food hygiene. The banquet kitchen caters for functions at the hotel.
NEA regulates the food retail industry in Singapore and ensures that food sold at retail outlets is prepared hygienically and thus safe for consumption. It licenses all food retail businesses, such as restaurants, cafes, snack bars, supermarkets, mobile food wagons and food caterers.
Eating establishments and food stalls are assessed by NEA and given the grades. Grade A indicates a score above 85 percent, B implies anywhere between 70 percent to 84 percent, C between 50 percent to 69 percent while lowest score of D is anywhere between 40 percent to 49 percent.