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

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

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

Hong Kong found the amount of melamine in two popular Koala's March chocolate-filled cookies were 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.