Zhang Yujun and Zhang Yanzhang are accused of illegally concocting and selling the so-called "protein powder," made up mostly of melamine and malt dextrin, the state-run Xinhua news agency reported. The powder was added to raw milk to make it appear high in protein content, the report said.

The melamine-tainted milk powder sickened tens of thousands of Chinese babies, adding to the country's woes stemming from food and product issues.

The two are accused of producing 600 tons of the fake protein powder from September 2007 to October of this year, the report said, adding that police had found their illegal production workshop in Shandong Province, the largest source of melamine in the country.

Sanlu Group in Shijiazhuang, along with other dairy brands such as Mengjiu and Yili, became the focus of investigation after the scandal broke.

Sanlu stopped production Sept. 12, recalled more than 10,000 tons of its baby formula products, and recently filed a bankruptcy petition, facing debts of 1.1 billion yuan ($161 million), the report said.