Halal buffet restaurant Royal Palm at Orchid Country Club had its hygiene grade adjusted down to a "C" on Wednesday, after 65 people fell ill from eating there last year.
The National Environment Agency (NEA) said in an advisory on Wednesday that the revised hygiene grade was due to an outbreak of a suspected food-borne illness.
The 65 diners reported having stomach flu symptoms after consuming food from the restaurant, which is on the ground floor of Orchid Country Club's social clubhouse, on Oct 30 and Nov 20 last year, the NEA added.
According to its website, the restaurant has a seating capacity of 350 and hosts weddings and corporate events as well.
It is known for its halal lunch and dinner buffets, which cost up to $35++ per adult.
Checks online show that the restaurant is owned by the Singapore Hospitality Group, which also runs a chain of halal eateries such as The Landmark, Warung Nasi Pariaman and I AM @ Tampines Hub.
In the advisory, the NEA said that it will review the restaurant's hygiene grade a year from April 4, and will keep the premises under surveillance in the meantime.