Federal Treasurer Wayne Swan has accused some mining companies of intimidating other businesses from publicly supporting the Government's mining tax package.
Resources companies are running a strong campaign against the proposed 40 per cent tax.
The Government says it is still negotiating with the industry about aspects of the proposal and transitional arrangements.
But Mr Swan has told Channel Ten some companies are acting dishonourably, although he declined to say who.
"Unfortunately, behind the scenes a small number of companies are using strongarm tactics to silence other companies, both in the mining sector and more broadly in the economy, from commenting favourably," he said.
Nationals Leader Warren Truss has dismissed that suggestion.
Mr Truss told the ABC's Insiders program the industry has a right to defend its interests.
"The Government's case on this is pretty incredible," he said.
"They asked us to vote for a CPRS so we would emit less carbon, they asked us to vote for higher taxes on cigarettes so we would smoke less, they asked us to vote for a higher tax on alcopops so we would drink less" he said.
"But somehow or other a big new tax on mining is going to make us do more mining. It's simply a nonsense."
Minerals Council head Mitch Hooke is disappointed by Mr Swan's accusations and says they are part of a Government campaign against the sector.
"We have this new attempt to besmirch the industry's reputation, so again, it's just a continuation of an attempt to denigrate and demean one of Australia's premier industries as justification for a tax grab in lieu of tax reform," he said.
He called on Mr Swan to name the companies he claims are pressuring others.
"I am not aware and I am pretty sure I would know if there was any kind of strongarm tactics going on within the industry," he said.
"The Treasurer should put the case on the table substantiate these claims."