Officials said that traces of melamine were found in powdered milk manufactured by Arla, the Copenhagen Post reported. The substance has now been discovered in milk from 22 companies.
Arla has suspended production at an infant formula plant and recalled some other dairy products, including fresh milk, yogurt and ice cream.
Signs of melamine poisoning have been found in more than 6,000 infants and at least three have died. Experts say the substance, generally used in plastic manufacturing, may have been put in milk to increase its protein content.
Last year, melamine in pet food killed hundreds of dogs in the United States.
At least four people have been arrested in China.