Immigration authorities have taken punitive action to bar the Japan Institute of Management-Labor Science from accepting foreign vocational trainees over the next three years, institute sources said Wednesday.

A sewing factory in Aichi Prefecture was found to have made three Chinese trainees, introduced by the institute last year, work extended hours beyond their prescribed limit, and the institute has admitted to inadequate supervision, they said.

The institute, which is required to monitor and report on private firms that have foreign trainees, failed to prevent three Chinese trainees from working overtime at a sewing plant in Aichi Prefecture, they said.

It has accepted too many trainees and failed to monitor them adequately, they said.

The institute is under the control of the Health, Labor and Welfare Ministry and is now headed by a former chief of the Tokyo Immigration Bureau.