Story highlights The Chinese dairy company 'sincerely' apologizes to customers for the problems

The products, containing high levels of a potentially carcinogenic substance, have been destroyed

The company says the products did not go on sale and remained in storage

Chinese microblog users urge others to boycott the company's products

Criticism of lax food safety standards at Chinese companies abounded on microblogging sites in China on Tuesday following the latest scare involving dairy products in the country.

Tests found that cartons of milk made by Mengniu Dairy Co., the largest Chinese dairy company, had excessive levels of aflatoxin M1, a substance that can cause liver cancer.

The tests were carried out by the Chinese Administration of Quality Supervision in an inspection of nationwide milk products on Saturday.

The toxin came from contaminated feed consumed by the cows that produced the milk, China's official news agency, Xinhua, reported.

The milk cartons did not make it to market but remained in storage during the inspection, according to a statement from the company on Sunday. Mengniu said that it had destroyed all the toxic milk as it sought to reassure consumers on its commitment to product safety.

Mengniu "once again would like to sincerely apologize to all consumers," said the statement. "We should earnestly learn from this lesson and comply with state and company quality and inspection standards with precision and care, making sure our product quality from every sector is approved in the future."

Users commenting on Chinese social media sites offered scathing opinions about the management of Chinese companies following Mengniu's admission of problems.

"Businesses in China are destroyed by Chinese businessmen themselves," said one user on Sina Weibo, the Chinese equivalent of Twitter. "Don't ever blame us on buying foreign goods."

"If I have a baby one day, I will also buy safer milk powder produced overseas," the user wrote Tuesday.

"Let us boycott Mengniu altogether, show the shameless businessmen our strength." said a posting by another user.

Food safety scandals have blighted the dairy industry in China since 2008, when melamine-tainted milk killed at least six babies and caused kidney stones and urinary tract problems in hundreds of thousands of children.

Twenty-one people were tried and sentenced for their roles in the scandal, and two of them were executed.

In April, the police in Southwestern China seized more than 26 tons of melamine-tainted milk intended for use in ice cream, according to local officials.