Nineteen out of 291 meat samples have been found with a trace amount of preservative sulphur dioxide, the Centre for Food Safety says. The chemical should not be used in fresh or frozen meat.

The centre collected 291 meat samples for tests and 15 beef and four pork samples contained sulphur dioxide at levels between 10ppm and 2,100ppm.

Based on the levels detected, normal consumption should not pose any adverse health effects. But people who are allergic to the preservative may experience respiratory discomfort, headaches and nausea.

The centre has collected follow-up samples and issued warning letters to the shop operators concerned. If there is sufficient evidence they will be prosecuted.

The centre urged the food trade not to use preservatives in fresh or frozen meat and to comply with legal requirements. It also reminded people to buy meat from reliable stalls.