The campaign by the big miners against Brendon Grylls' mining tax continues with a new resources industry-commissioned report claiming it would cost 7200 jobs.
The WA Nationals' leader has proposed a controversial hike in the rental fee paid by BHP Billiton and Rio Tinto from 25 cents to $5 a tonne, arguing that the state's two biggest miners can afford to and should pay a fairer share into the public coffers.
The Minerals Council of Australia - which counts BHP and Rio as members - commissioned a report that argues the proposed new tax on iron ore would lead to the loss of 2900 jobs in the Pilbara region, 3400 in WA in total and 7200 nationally.
The researchers Deloitte Access Economics say the lift in production costs would discourage BHP and Rio from further investing and so shrink the economy and cost jobs.
"Its impact would see the Australian economy eventually shrink by $2.9 billion a year as a result of a tax that raised $2.3 billion," MCA chief executive Brendan Pearson said.
Deloitte also argued WA's economy would be most affected by the supposed loss in mining activity and after allowing for resultant losses in GST grants the revenue for it would be less than $300 million per year.
Premier Colin Barnett recently argued that WA's economy remained the nation's strongest, despite declines in the last three years but many economists predict it will continue to decline in the next three years due to less mining investment.
Mr Grylls says the new charge will raise $7.2 billion for government coffers over four years, which was needed because the state was not getting its fair share of GST revenue at the expense of the other states.
He has dismissed various industry groups including the Chamber of Minerals and Energy WA and state Chamber of Commerce and Industry for running what he says is a multi-million dollar alarmist campaign funded by iron ore profits.
The MCA spent $17.2 million on mostly TV ads to campaign against former PM Kevin Rudd's planned resource super profit tax in 2010, previously released Australian Electoral Commission figures revealed.