The chemical was found in milk tablets, a food supplement made of concentrated milk, produced by Inner Mongolia Li Cheng Industrial in China, the Centre for Food Safety said in a statement.

The agency also found excessive melamine in three Chinese-made cookie samples produced by Japan's Lotte China Foods. Lotte's products were earlier confirmed to be tainted by Macau authorities.

Hong Kong found the amount of melamine in two popular Koala's March chocolate-filled cookies was 57 and 68 parts per million - much higher than the legal limit of 2.5 ppm.

The third sample of the brand's strawberry-flavored cookies contained 4.3 ppm of melamine.

The centre said it has asked importers to recall the tainted products and urged retailers to stop selling them. It did not rule out prosecution later.

Major supermarket chains Wellcome and PARKnSHOP had already removed the Lotte products manufactured in China from their shelves on Friday following Macau's announcement that melamine had been found in cookie samples.

Calls to Lotte China Foods in Beijing and Li Cheng's office in Hohhot in northern China's Inner Mongolia region were unanswered late Saturday.

An official at Lotte (China) Investment in Shanghai said on Friday the company would inspect all of its products again following Macau's test results.

China is facing a severe food safety crisis which started with melamine-laced infant formula but has spread to dairy and other food products.

On Friday, Hong Kong found melamine in Heinz vegetable cereal for infants and Silang House-brand steamed potato wasabi crackers, both manufactured in mainland China.

Melamine-contaminated milk has killed four babies and sickened more than 50,000 children in mainland China. Six children in Hong Kong and Macau have been found with kidney stones after drinking tainted Chinese milk.

Chinese suppliers trying to boost output are believed to have diluted their milk while adding melamine because its nitrogen content can fool tests aimed at verifying protein content.

Health experts say ingesting a small amount of melamine poses no danger, but larger amounts of the chemical, used to make plastics and fertiliser, can cause kidney stones and lead to kidney failure.

Infants are particularly vulnerable. -- AP