"The tainted eggs were found in some batches of egg products made by certain manufacturers," Sun said when inspecting egg production in Dingxing county in north China's Hebei Province. He did not elaborate on the issue.

Wang Zhicai, director of the ministry's husbandry and livestock division, said earlier the tainted eggs produced by Dalian Hanwei Enterprise Group and found in Hong Kong was a specific case and using melamine in feed production is not hidden industry rules.

Industry experts said the majority of the country's egg products was of good quality and safe, and the recent tainted egg scandal might be a result of melamine-contaminated feed.

According to official figures, in recent 22,700 batches of feedstuff quality check on melamine, 97.61 percent were found up to standard.

The quality of the country's feedstuff had been generally improved during recent years, Sun said, but there were still illegal producers adding hazardous chemicals and drugs into their products.

He urged nationwide quality control departments to carry out scrutiny checking of animal feedstuff, ensure product safety and promote the healthy development of the industry.