Queensland's energy minister has denied publicly owned electricity generators are overbidding in the wholesale power market and driving up prices for consumers.
Household and business electricity bills will surge at least nine per cent across Queensland, with firms in the southeast set to cop a 19.8 per cent rise in 2022/23.
Retail bills are rising on the back of wholesale electricity prices quadrupling to $171 per megawatt hour in the year to March.
Climbing international coal and gas costs lifted Queensland wholesale prices to $283 MW/h - the highest level on record - in May.
Energy Minister Mick de Brenni has denied state-owned generators Stanwell Corporation and C S Energy have been price gouging on the National Electricity Market.
"Publicly owned generators bid to cover generation costs," he told AAP.
"Any revenues above costs are given back to Queenslanders through Asset Ownership Dividends."
To cope with surging retail prices the state government is granting households a one-off $175 rebate on power bills, but businesses are on their own.
In 2017, the state government intervened in the market to order Stanwell and C S Energy to alter their bidding practices, which led to dramatic falls in wholesale and retail prices.
Liberal National Party energy spokesman Pat Weir said there was growing evidence the two generators were rorting the wholesale market with "exorbitant bidding practices".
He accused the government of using generators to overbid on spot prices to make excessive profits, with only a fraction of the finances returning to Queenslanders via the rebate.
"Queensland has the highest electricity prices in the country," Mr Weir said in a statement.
"If the state government keeps this up, prices will skyrocket even higher. It's costing households. It's costing businesses.
"The Palaszczuk government must act before businesses go broke and the rising cost of living pressures hit Queenslanders even harder."
AAP has sought comment on bidding practices from the operators of Queensland's other 14 private coal and gas-fired power plants: Arrow Energy, Alinta Energy, Intergen, Origin Energy, QGC and RATCH Australia.
Alinta Energy refused to comment on "commercially sensitive information of this nature" when asked if the company had bid more than generation costs on the wholesale market.
"What we will say is that, a. We have no upstream operations, and b. The pressures on the market are clear for all to see," an official told AAP in a statement.
Another two of the six private companies operating coal and gas generators declined to comment, but told AAP the NEM is a "highly regulated" market.
The Chamber of Commerce and Industry Queensland has called on the government to shield businesses from electricity price spikes, as it is doing with households.
"We know rebates have worked in the past as an appropriate mechanism to relieve power bill pressure, especially for small businesses," CCIQ's Cherie Josephson told AAP.
"We support a rebate for those impacted under Tariff 20, the most common for small businesses."
She said the CCIQ was particularly concerned about large businesses, whose bills will surge 21.2 per cent.