Three people in Shanghai have been prosecuted for allegedly producing and selling toxic milk powder, local officials said Thursday.

The corporate representative of the Shanghai Panda Diary Company, and its general manager and deputy general manager were prosecuted on suspicion of producing and selling tainted milk powder, said Sun Yeyao, an official with the Shanghai Bureau of Quality and Technical Supervision.

In an examination this year, the company's four batches of milk powder and four batches of milk flavoring were confirmed to have excessive melamine, which can cause kidney stones and kidney failure, Sun said.

The supervision department has suspended operation of the company and sealed up all its stocks. Working groups were dispatched to oversee the company to recall its products in seven regions, Sun said.

The company allegedly used concentrated milk that had been confirmed to have excessive melamine last year to produce milk powder, he said.

Some of its toxic material was provided by the Ningxia Panda Diary Company. Public security department of northwest China's Ningxia Hui Autonomous Region has been probing into the case, Sun said.