Mining companies believe they are being used for political purposes by being forced to appear before a Senate inquiry into an industrial relations bill put forward by One Nation, when they are already dealing separately with the government on the same matter on the basis of confidentiality.

The Minerals Council of Australia, BHP and Anglo American Australia will testify at Wednesday’s inquiry by a Senate committee into a bill proposed by One Nation senator Malcolm Roberts aimed at stamping out labour hire in the coal, airline crew, stevedoring and nuclear science industries.