Japan said it will send food-safety officials to China to study how pork dumplings became contaminated with a pesticide that sickened at least 10 Japanese.

"Japan and China have agreed to cooperate in order to find the cause," Chief Cabinet Secretary Nobutaka Machimura said yesterday during a regular press briefing. The team will leave in the next few days, he said.

Japan's decision to send officials to China follows a Feb. 1 warning by Foreign Minister Masahiko Komura that the food scare could damage Japan-China ties, and his call for the countries to find the source of the poisoning together. A group of Chinese officials arrived in Tokyo yesterday.

Machimura today said health officials have so far confirmed 10 cases of food poisoning from Chinese-made pork dumplings. More than 2,000 people concerned about dumplings made in China or afraid they have been poisoned have contacted local health ministries in Japan, he said.

Japan's delegation to China will leave tonight and includes officials from the health and agriculture ministries, Machimura said.

The Japanese inspectors will visit pesticide retailers and farmhouses near the factory that produced the contaminated dumplings, he said.

"The clues don't lead to one clear possibility," said Toshio Maki, an assistant professor at Tokyo Seiei College who specializes in food poisoning.

"It's hard to imagine the chemical was added in Japan where researchers can only obtain it in small amounts for research."

Japan Tobacco Inc., Maruha Corp. and Ajinomoto Co. recalled products supplied by Tianyang Food Co. last week, and the Japanese government found a pesticide called methamidophos in food made by the company.