Queensland's corruption watchdog has been asked to investigate whether Deputy Premier Jackie Trad engaged in an act of "extortion" against mining companies.
Ms Trad has told miners she won't raise coal royalties for three years if they volunteer to put $70 million into a new regional infrastructure fund.
Opposition leader Deb Frecklington has written to the head of the Crime and Corruption Commission, saying the circumstances that led to the fund "may constitute an offence of extortion under section 415 of the Criminal Code 1899".
Ms Frecklington says the deputy premier's proposal is essentially a $70 million ransom note.
"This is extortion, it is blackmail, no matter how you look at it," she has told reporters.
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"This is a shakedown of the resources industry to try to prevent them from ever opening a new mine in Queensland again."
Whatever position mining companies take on the fund, Ms Trad has ruled out increasing coal royalties in next month's state budget.
The issue will be revisited next year if miners don't sign up.
On Wednesday, Ms Trad told reporters she expected a response from the miners 24 hours later.
But on Friday a spokeswoman for the deputy premier said discussions were still ongoing, and that the Opposition's referral was a cheap political move that would waste the CCC's time.
"(The) leader of the Opposition's comments are ridiculous," the spokeswoman said.
"It's disappointing that the LNP is wasting the CCC's time in this way."
Premier Annastacia Palaszczuk said the fund was just another way to help resource-based communities and there was nothing particularly unusual about it.
"I don't think the deputy premier or the government has done anything wrong there. It is a voluntary scheme," she told reporters in Bundaberg.
