The Consumer Council on Tuesday urged manufacturers of preserved vegetables to step up quality control, after finding contaminants such as insects and hair in almost all the products it tested.

The watchdog said it ran tests on 30 samples of preserved vegetables, including kimchi, sauerkraut and gherkins, and all but one contained something they shouldn't, including mites, bits of metal and pieces of plastic.

Three pickled mustard leaf with olives products had between 91 and 310 fragments of insects in each 100-gramme sample, the watchdog said.

"I don't expect when you open a [packet of] preserved vegetables to find hundreds of these insect pieces there. I think a few is already too much," said Nora Tam, who chairs the council's research and testing committee.

"As an ordinary person, if suddenly you find some insect legs on your dish, will you like it? Of course, not."

Tam said although the contaminants might not be harmful, the situation is far from satisfactory.

"That's why for some samples which got very high content of these impurities or filthy materials, they should improve their production process, the manufacturing process, and give us better quality products for us to consume. For those with a few, I think that's sometimes unavoidable," she said.

The council also said that more than 85 percent of the preserved vegetables it tested were high in sodium and people shouldn't eat such products as a substitute for fresh food.