A seafood company that was allegedly involved in exporting pesticide-tainted frozen mackerel to Japan said yesterday that it had never purchased, stored or used fatal pesticides during its processing operations.

The company also said that the 18 samples including raw materials and packages, which it had selected for tests, were free of the pesticide, Miao Qiang, president of the Shandong-based Weihai Yuwang Aquatic Foods Co Ltd, said.

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