GUANGZHOU - Authorities in Guangzhou, capital of South China's Guangdong province, said Sunday that they have discovered mildew contamination in some infant formula products during an ongoing dairy safety overhaul.

Excessive amounts of aflatoxin were detected in five formula products that were produced between July and December last year in Central China's Hunan province, according to a statement issued by the municipal industry and commerce department.

Four of the products were produced by Ava Dairy Co?Ltd. Ava Dairy based in Hunan's capital of Changsha, while the fifth was produced by Hunan Ava Dairy Holdings Co Ltd., the parent company of Ava Dairy, the statement said.

The department has ordered retailers to suspend sales of the products pending further investigation.

Food safety authorities in Changsha city on Sunday launched a comprehensive investigation of the companies following the news in Guangzhou.

Aflatoxin is produced by a fungus that commonly grows on grain and peanuts. High levels of the toxin have been shown to lead to cancer in animal tests.