Discrepancies in testing results for StarLink between Japan and the US should be resolved by the end of the week, US agriculture secretary Ann Veneman announced on Wednesday.

Japan found traces of StarLink in one of five samples sent on 15 January by the US for food use, but the same samples tested negative at a USDA laboratory before leaving the country.

Japan’s Health, Labour and Welfare Ministry sent a team to the US this week to monitor how USDA officials test for StarLink in the US corn harvest. The USDA sent officials to Japan last month to observe testing.

Veneman said the USDA “hopes to make additional progress this week and hopefully resolve it.”

Bio-corn StarLink is manufactured by France’s Aventis SA but is banned by the US for human use because of concerns that it might cause allergic reactions. The corn is however approved for animal consumption in the US.

The discovery of the gene-altered corn in taco shells last September saw the recall of more than 300 US foods, while a consumer group in Japan has also revealed that the corn has been found in a food product for human use there.