Chinese-made dumplings blamed for a food-poisoning outbreak in Japan were unlikely to have been contaminated in China, Beijing's top investigator says.
Thousands of people reported feeling ill after eating the food
Traces of an insecticide were found in the dumplings, but security chief Yu Xinmin said there was "little chance" the chemical was added in China.
Both Tokyo and Beijing say the food was sabotaged deliberately - but each says the crime did not happen on its soil.
Ten people fell ill after eating the frozen dumplings in January.
Thousands more reported sickness as the issue gained massive media coverage across Japan, straining relations with its neighbour.
The product was later found to contain the highly-toxic pesticide methamidophos.
"After comprehensive investigation, we believe there's little chance that methamidophos was put into dumplings in China," said Mr Yu, of the Ministry of Public Security.
Although he stopped short of saying the food was contaminated in Japan, he accused Tokyo of not co-operating with his investigation.
Mr Yu, recently returned from a fact-finding mission in Japan, said the police there refused him access to "relevant material evidence".
But Japan's chief of police, Hiroto Yoshimura, rebuffed Mr Yu's claims.
"We have presented all valuable documents to the Chinese side, so I cannot understand why they expressed regret," Japan's Kyodo news agency reported him as saying.
"We cannot easily provide the dumplings, their bags and other material evidence as requested by the Ministry of Public Security as we have taken procedures to seize them.
"But [we] are ready to provide them if a request is filed by the Chinese side in order to identify the suspect and build a criminal case."
China has been hit by a string of food and product safety scandals in recent years - including tainted toothpaste, contaminated pet food and high levels of lead in toys.
Beijing introduced new laws last year aimed at tightening national standards in food production.