BEIJING - A Chinese seafood company that was allegedly involved in exporting pesticide-tainted frozen mackerel to Japan said on Tuesday afternoon that it had never bought, stored or used fatal pesticides during processing.

The company also said that the 18 samples including raw materials and packages, which it had selected for tests, were free of the pesticide.

"We started investigations into the mackerel products immediately after learning that a Japanese non-governmental testing organization detected fatal pesticides in our exports," said Miao Qiang, president of Weihai Yuwang Aquatic Foods Co. Ltd., which is based in the eastern Shandong Province.

Kouzai Bussan Co. Ltd., a Japanese frozen food company, said on Monday that pesticide was detected in frozen mackerel processed in and imported from China.

While the residue standard of dichlorvos for fishery products is set at 0.01 parts per million (ppm) under Japan's food sanitation law, 0.14 ppm of the pesticide was detected in frozen mackerel processed in China, according to Japanese media.

The mackerel were imported from Denmark and all supplementary materials except salt were provided by the Japanese company, said the Chinese company.

"We were shocked by the news, but with a view of protecting the consumers' health, our company has taken a series of protective measures including suspending export of relevant products," Miao said.

"But the allegedly tainted products were exported eight months ago, so it takes time to find out what happened to them. We hope both sides would cooperate to solve the problem," said Miao.