A Thai dairy producer said Thursday it plans to return 122 tons of newly imported powdered milk to China even before tests have determined whether they are contaminated with the banned chemical melamine.

Thailand's Food and Drug Administration has been impounding newly imported milk powder from China at ports around the country, pending laboratory analysis.

Milk tainted with melamine has been blamed for killing four Chinese babies and sickening more than 50,000 others, sparking global concerns about food products made with Chinese milk or milk powder.

The scandal has sparked global concern about Chinese food imports and recalls of Chinese-made products including milk powders, biscuits and candies across the globe.

Chinese authorities believe suppliers trying to boost output diluted their milk, adding melamine because its nitrogen content can fool tests aimed at verifying protein content.