The head of the Chinese delegation in Japan for talks over recent food poisonings said Wednesday he believes the Chinese-made frozen "gyoza" dumplings were deliberately tainted with pesticide after being shipped from the factory and not during the production process.

Speaking at a joint news conference with the Japanese side in Tokyo, Li Chunfeng stressed that Tianyang Food's factory in Shijiazhuang, Hebei Province — where the tainted dumplings were made — has strict and thorough quality control measures that made it almost impossible to mix the toxic substance there.

"I believe that the incident did not stem from structural problems but rather is a specific case," Li, vice director of China's Import and Export Food Safety Bureau at the General Administration of Quality Supervision, Inspection and Quarantine, said after morning talks with the Japanese officials.