The poisoning incident in Japan caused by dumplings imported from a food plant in northern China was a special case of sabotage and it's unlikely it happened in China, said China's security and quality watchdogs on Thursday.

"After comprehensive investigation, we believe there's little chance that methamidophos was put into dumplings in China," said Yu Xinmin, deputy director of the criminal investigation bureau with the Ministry of Public Security, at a press conference.

The General Administration of Quality Supervision, Inspection and Quarantine (AQSIQ), China's quality watchdog, also told press that it came to the same conclusion after finding no harmful chemicals in relative products and samples and no abnormal operations on the part of the Chinese producer.

Japanese media reported in January that 10 people fell ill in Japan after consuming frozen meat dumplings produced by Tianyang Food Plant based in north China's Hebei Province.