Audits by the Fair Work Ombudsman have found up to 40 per cent of foreign workers employed under 457 visas were underpaid, not performing the jobs they were supposed to do or no longer employed by the person who sponsored their entry into Australia.

Fairfax Media has obtained monthly 457 visa monitoring reports prepared by the Fair Work Ombudsman which identify hundreds of cases of reported underpayment of foreign workers and other problems with the temporary skilled migration system.

The reports appear to conflict with the clean bill of health given to the 457 program by Immigration Minister Scott Morrison. Credit:Alex Ellinghausen

The reports appear to conflict with the clean bill of health given to the 457 program by Immigration Minister Scott Morrison on Wednesday as he unveiled changes that would make it easier for employers to import labour.

A government report, Robust New Foundations, proposes a "fast-track" approvals process for larger companies with good records, relaxed English-language requirements and consideration of a 10 per cent reduction in the $53,900 maximum income threshold.