Japanese fashion chain Fast Retailing Co. says it will expand monitoring of factories operated by its suppliers following complaints over labor violations and other problems.

Yukihiro Nitta, who is in charge of corporate social responsibility at the fashion giant, said Wednesday its oversight would extend to the fabric manufacturers who supply the garment companies that make clothes for Fast Retailing.

The company earlier announced broad plans to tighten controls on working hours and other conditions for workers at factories that are mostly in developing countries such as China, Vietnam, Cambodia and Bangladesh. That followed a report by labor rights groups detailing specific problems at some factories.

It says it will increase surprise audits of indirect suppliers such as textile makers and conduct training on labor rights for workers and managers.