Uniqlo owner Fast Retailing has decided to inspect third-tier suppliers of clothing materials for working conditions and human rights compliance, extending checks currently run on higher-tier suppliers, reports Nikkei Asia.

The Japanese company will apply its code of conduct to third-tier spinning mills that supply cotton threads for Uniqlo products. Weekly working hours for a laborer, including overtime, will not exceed 60. Third-party investigators will check the suppliers roughly once a year for compliance with the code of conduct. If a third-tier supplier is flagged as needing improvement, random follow-up audits will gauge progress.

Fast Retailing receives third-party certification authenticating that cotton used in its products has no connection to forced labor. But in 2021, U.S. officials blocked imports of Uniqlo shirts, citing insufficient evidence that they were free from forced labor.

With countries around the world toughening oversight, Fast Retailing put together a team of about 100 people to improve traceability in the supply chain. The team worked with sewing plants and fabric mills to identify cotton mills further upstream for each product.

Fast Retailing had originally performed compliance checks only on 800 or so plants operated by primary and secondary suppliers. Lower-tier suppliers were expected to adhere to the code of conduct through the intervention of higher-tier suppliers.

Now, Uniqlo will handle compliance checks for third-tier cotton spinning mills to see conditions on the ground and ensure that the code of conduct is being followed.