A major test case of federal Labor’s same work, same pay laws has been told BHP paid thousands of workers at three Queensland mines up to $49,000 less each year than directly employed staff doing identical jobs because they were employed through subsidiaries and labour-hire companies.

The Mining & Energy Union and Australian Manufacturing Workers’ Union are seeking orders in the Fair Work Commission that the workers on the mines employed by contractors or subsidiaries should be paid the same as their on-staff peers.