Two seasonal food samples have failed the Centre for Food Safety's microbiological tests.

The centre collected 304 samples of buffet food, including seafood, salad, cold dishes, sushi and sashimi, and 22 samples of poon choi - literally "big bowl feast" - for tests.

One poon choi sample contained Bacillus cereus at a level of 3.7 million per gram while the other poon choi sample had Staphylococcus aureus at a level of 8 million per gram.

The samples were taken from restaurants. The centre has issued warning letters to the operators, stepped up inspection of the restaurants and taken more samples for tests. The centre will consider taking out prosecutions if there is sufficient evidence.

Consumption of food containing a high level of Bacillus cereus or Staphylococcus aureus may cause gastrointestinal discomfort.