A four-member team will soon leave for Japan to help investigate a food poisoning incident allegedly caused by imported Chinese frozen dumplings, Chinese authorities said on Friday.

"The team will help the Japanese side to probe the case," the General Administration of Quality Supervision, Inspection and Quarantine (AQSIQ) information office told China Daily.

Along with AQSIQ officials, the team will include representatives of Ministry of Commerce, Hebei province's Inspection and Quarantine Bureau and the Chinese Academy of Inspection and Quarantine.

"The team is now waiting for notification from the Japanese Embassy in Beijing. It's expected to leave very soon," said the statement.

Japanese media reported on Wednesday that at least 10 people in three families in Hyogo and Chiba prefectures suffered stomachache, vomiting or diarrhea after eating frozen dumplings made by Tianyang Food Processing in northern China's Hebei province.

The dumplings are alleged to be contaminated with traces of methamidophos, an organic phosphorus insecticide.

The reports have triggered concerns over Chinese-made food products in Japan.

The Yomiuri Shimbun, a leading Japanese newspaper, reported the number of people who claimed to be sick as a result of eating frozen food products from China had risen to 511 in 33 prefectures as of Friday afternoon. However, no fresh cases have so far been confirmed.

But a preliminary investigation report released by AQSIQ on Thursday showed no harmful chemicals were found in samples of the frozen dumplings blamed for the incident.

Wang Daning, director of AQSIQ's import and export food safety bureau, said on Thursday the Japanese side had told the administration that traces of pesticide were found only in the 10 victims' vomit and packages of the dumplings they had eaten, but not in others from the same batches.

He did not rule out the possibility of deliberate poisoning, and said police from both countries had intervened.

As a precaution, the Chinese government has ordered Tianyang Food Processing to halt production and exports. The company has been ordered to recall all its products from both the domestic and foreign markets, according to AQSIQ.

Japanese Chief Cabinet Minister Nobutaka Machimura said on Friday he thought Beijing was taking the incident seriously.

"China's response has been very speedy. It's stopped production and started inspections," Machimura told a news conference.

Experts are also calling for careful handling of the issue so as not to harm ties between the two countries.

"It's irresponsible to make early conclusions and blame China for it before the final results are released," Gao Hong, a researcher from the Chinese Academy of Social Sciences, said.