The announcement came as new Zealand Prime Minister Helen Clark said she learned about the issue on September 5 and directed her senior ministers to coordinate with provincial officials in China to inform their superiors.
Sanlu Group Co., the company that manufactures the milk powder contaminated with melamine, is 43 percent owned by New Zealand dairy group Fonterra.
Li Changjiang, head of China's General Administration for Quality Supervision, Inspection and Quarantine has confirmed the milk powder was contaminated with melamine, an industrial chemical used in plastics.
The contamination was believed responsible for some 580 babies to develop kidney stones, a rare disease among babies.
The controversy also forced Chinese health authorities to seize 2,176 tons of powder from a Sanlu warehouse and recall 8,218 tons already sent to market.
Fonterra chief executive Andrew Ferrier is eyeing sabotage on the issue and quoted China's Health Ministry which says that the melamine was added during the delivery. They suspect raw milk producers as responsible.
"It is impossible to totally exclude sabotage of the product and that's where we are in this case," Ferrier said.
Fonterra, the world's biggest milk trader, added it had instructed Sanly to recall the product as early as six weeks ago, but the move was implemented only last week.
