Despite the claims by Treasurer Wayne Swan that some mining executives admitted privately they can pay more tax, a number of business leaders are still opposing the proposed super profits tax.

Conditions of the proposal include a 40 per cent mining tax on profits above a six per cent threshold from 2012 for mining companies.

Several of the State's prominent business executives have signed a joint letter, requesting Prime Minister Kevin Rudd for a reconsideration on the mining tax.

Signatories to the letter include John Hughes, Andrew Forrest, Dale Alcock and Gina Rinehart.

James Pearson, chief executive of the West Australia of Commerce and Industry, said that aside from the mining sector, the tax will also hit all businesses.

"Every business in the state, large or small, directly or indirectly, benefits from a strong and growing resources sector. That's why so many business leaders have decided to put their names to an open letter to the Prime Minister, asking him to rethink his decision,” Mr. Pearson said.

Mr. Pearson stressed that they do not want to put the resource sector at risk as it brings more revenue to WA.

“As major employers in Western Australia, they know that their success is like the success of so many others, big and small businesses, depends on a strong and successful resources sector.”