A poon choi sample collected from a Sheung Shui food factory has been found to contain two pathogens that cause gastrointestinal symptoms, the Food Safety Centre says.

A dried bamboo fungus sample was also found to have contained a heavy metal slightly exceeding the permitted level.

The centre has taken 184 samples during its latest test on Lunar New Year foods. All passed the tests except these two.

The centre's Principal Medical Officer Dr Tina Mok said inspections at the food factory found that its environment was acceptable. But problems were found in its food handling and temperature control.

The centre has issued a warning letter to it and ordered it to clean the premises thoroughly. Tips were also given to food handlers on how to prepare poon choi to avoid contamination.

So far the centre has received no reports of poon choi poisonings. Poon choi should be kept at 60 degrees Celsius or more after cooking.

The dried bamboo fungus sample was taken from a retailer in Wan Chai. As it only slightly exceeded the permitted level, normal consumption of it would not have harmed health.