Chinese officials have said the pesticide tainting frozen beans that made a Japanese woman ill last week did not come from the production process, and Japanese police suspect foul play.
The beans contained 34,500 time the legal limit of pesticide dichlorvos. Another 26 cases suspected to be connected came to light last week.
Samples from other packages of the beans and from China tested negative to the chemical, and the general manager of producer Yantai Beihai Foodstuff said the company had never used that type of pesticide.
Japanese police have aired suspicions the contamination may have been deliberate, because the washing and boiling process the beans go through would have diluted the chemical levels.
Japan's health ministry ministry ordered retailers to remove the beans from sale last Wednesday.