No harmful chemicals were found in Chinese dumpling exports involved in a food poisoning incident in Japan, said China's quality watchdog on Thursday.

The General Administration of Quality Supervision, Inspection and Quarantine said it conducted tests on the samples of the two batches of frozen dumplings causing poisoning Japan on Thursday morning and no trace of pesticide remains were found.

Tests on the raw materials being used by the factory such as ginger and cabbage show they are also safe.

At least 10 people in Japan's Hyogo and Chiba prefectures reported stomach ache, vomiting or diarrhoea after eating the dumplings, according to Japanese media.

The Japanese government had examined the vomit of the poisoned people and the food packages left at their houses, finding enough methamidophos, a pesticide substance, to poison humans, said Wang Daning, head of the Bureau of Import and Export Food Safety with the AQSIQ.

However, tests by Japanese authorities on the rest of the dumplings of the same batches sold in Japan, totaling more than 2,000 packs, were safe, so were all the other types of products made by the same Chinese company, said Wang at a press conference on Thursday.

Wang said AQSIQ has demanded the producer of the dumplings, the Tian Yang Food Plant in north China's Hebei Province, recall all products in and on the way to Japan immediately.

Wang said the company's products are all exported to Japan and not sold in other countries or domestically.

All dumplings and other products made by Tian Yang have already been withdrawn from the Japanese market, said Wang.

Police from Japan and China will jointly investigate into the case, and China will send experts to Japan help resolve the issue.

"The investigators of Japan and China have agreed not to release any subjective judgment before a final result comes out," said Wang, answering questions about the possibility of someone putting in poison deliberately.

The Tian Yang Food Plant has been making frozen and dried food for more than 30 years. Wang said the company has a sound quality control system, with samples kept for every batch of exports.

In 2004, the company had to recall a batch of its meat products from Japan after the discovery of excessive amounts of escherichia coli, which can cause diarrhoea. But Wang said that could have been caused by problems in storage or transportation. The web site of the Tian Yang Company showed that its total assets were more than 80 million yuan, with annual production of more than 30 million yuan in 2000 (one US dollar equals 7.1853 yuan).

(Xinhua News Agency February 1, 2008)