Japanese ham and sausage producer Itoham Foods has added 310,000 packs of goods to a recall list in a contamination probe, according to reports.

The recall of the goods produced on behalf of other clients follows the discovery of groundwater at an Itoham factory in Kashiwa that contained a level of a cyanogen compound exceeding the accepted standard.

The products were among 640,000 packs that Itoham had been asked to produce on behalf of ten clients. The "private brand" products were developed jointly between Itoham and major supermarkets or other companies operating chains, and were sold under the names of the stores.

The clients included Japanese Consumers' Co-Operative Union, Value Lawson, CGC Japan Co and Tokyu Store.

No illnesses have been reported in connection with the contamination, according to the Mainichi Daily News.