Australia's biggest mining and energy companies are scrambling to relocate thousands of workers to Western Australia and bracing for hits to production volumes and cost structures after the WA government sounded the death knell for fly in, fly out workers from the eastern states.

Less than a week after FIFO workers from the eastern states were made exempt from 14-day quarantine periods designed to slow the spread of the coronavirus into WA, the Chamber of Minerals and Energy in the state has warned members to expect the special treatment will be axed within days.