China's quality watchdog said on Wednesday that earlier reports saying dissatisfied Chinese workers deliberately contaminated Chinese-made dumplings that sickened 10 Japanese were "mere subjective guesswork". It suggested the two sides could form a joint team to conduct a thorough investigation on all possible processes.

The following is the timeline of China's investigation into the dumpling poisoning case:

-- Jan. 30: General Administration of Quality Supervision, Inspection and Quarantine (AQSIQ) made a public announcement to investigate the food poisoning case hours after it learned from the Japanese authorities that at least 10 people in the Hyogo and Chiba prefectures got sick since December after eating dumplings produced by the Tianyang Food Plant in north China's Hebei Province.

The Japanese authorities said a pesticide substance called methamidophos had been found in the vomit of those poisoned and in the food packages left at their houses.

-- Jan. 31: Tests conducted on two batches of dumpling samples revealed no traces of harmful remains as alleged in Japan. All production chains, including material choosing, processing and packaging, as well as transport, have passed the local and national inspections, the AQSIQ said.

The administration demanded the Tianyang company stop production and recall all products in and on the way to Japan immediately. Additional tests were conducted on dumplings produced within 11 days around October 1 and October 20 last year. No traces of the pesticide were detected.

-- Feb. 3: China sent an expert team to Japan to jointly investigate the case. The two sides agreed to refrain from making any subjective conclusion before a thorough investigation and a full exchange of views.

Samples of the exported dumplings recalled from the Japanese market were brought back to China for inspection. Still, no harmful components were found.

-- Feb. 4: The Japanese government sent a team of officials and experts to China to inspect the case.

-- Feb. 5: A joint investigation team of China and Japan conducted an on-the-spot inspection in the Tianyang Food Plant. No abnormality was traced, said both Japanese and Chinese investigators at a press conference the following day.

-- Feb. 12: AQSIQ made another inspection tour to the Tianyang Food Plant, checking the plant's production chains, production record and videos. Nothing unusual was found.

-- Feb. 13: AQSIQ told a news conference that earlier reports saying dissatisfied Chinese workers deliberately contaminated dumplings sickening 10 Japanese were "mere subjective guesswork".

Japanese wire service Kyodo reported on February 12 the food poisoning in Japan caused by China-made frozen dumplings was likely committed by a person or persons with a grudge against the management.

So far, the Japanese authorities have not provided China with the dumpling samples found from the poisoned people's houses, samples of victim's vomit, inspection reports or any other evidence.

(Xinhua News Agency February 14, 2008)