The Shijiazhuang Intermediate People's Court accused Zhang Yujun of producing 775 tonnes of "protein powder" which contained melamine from October 2007 through August 2008. If added to, the product would make raw milk appear high in protein content.

Zhang sold more than 600 tonnes with total sales value of 6.83 million yuan (US$998,000), the court heard.

Zhang Yanzhang, sold 230 tonnes to others for Zhang Yujun.

The "protein powder" was sold to milk collectors in Shijiazhuang, Tangshan, Xingtai and Zhangjiakou cities in Hebei. Some collectors added it to raw milk and sold it to Shijiazhuang-based Sanlu Group, the country's major dairy at the center of the tainted milk scandal.

Other major Chinese dairy brands such as Mengjiu and Yili were also found to have melamine contents higher than the national food safety requirement in some of their products.

Sanlu stopped production on September 12. A bankruptcy petition for Sanlu has been filed as it faced 1.1 billion yuan of debt, the Shijiazhuang city government said on Thursday.

The Ministry of Health has said it was likely the contamination killed six babies. Another 294,000 infants suffered from urinary problems such as kidney stones.