The proposed resource super profit tax prepared by Wayne Swan has faced another disapproval, this time from former banker and mining leader John Ralph, stating the move as risky.

Mr. Ralph also refuted Swan's statements that resource companies were under taxed.

A business leader, Mr. Ralph issued an open letter, warning that the tax will damage the national interest by increasing sovereign borrowing costs. The warning follows after Mr. Swan yesterday accused mining leaders of lying about the RSPT and demands that they “accept the right of a government to govern.”

According to a research data author, miners only paid an effective rate of 27.8 per cent, which increased to 41.3 per cent including state royalties.

The coalition attacked the research authored by PhD student Kevin Markle and Professor Douglas Shakelford, stating the work as “the shonkiest.”

Professor Shakelford angrily defended its research, telling the opposition it was wrong to describe the work as a graduate paper, however, he admitted the research have reached its limitations on its use for formulating policy in “one sector of one economy.”

“The paper is a draft form and likely will undergo additional revision before publication in a peer-reviewed journal. Moreover, the paper's usefulness in formulating policy for one sector in one country should not be overstated,” he said.

“The purpose of the paper is to collect all data about the corporate income taxes paid by all publicly traded firms worldwide and thus provide a starting point for comparing one country with another.”

Meanwhile, mining companies continued to lobby against the tax. Rio Tinto chief executive Tom Albanese attacked the tax, stating it damages the Australian reputation by driving investments away.

Mr. Albanese also described the tax as his “number one sovereign risk on a global basis.”

Mr. Ralph agreed with Mr. Albanese, stating that a possibility on sovereign risk is very large.

"This will heighten significantly the sovereign risk assessment of Australia when it comes to investment in, and lending to, Australian entities... This changed assessment of risk will be priced into transactions and make borrowing more expensive for a country very dependent on foreign capital,” he said through a written statement.

Mr. Ralph is worried the mining tax will affect all Australians.