The WA Opposition claims the state government is risking investors' dollars with an environmental review into greenhouse gas emissions from the multi-billion dollar Wheatstone natural gas project.
Environment Minister Stephen Dawson has asked the Environmental Protection Authority to review annual emissions reporting by Chevron at its Wheatstone project, which came online in October.
Opposition leader Mike Nahan says the issue of CO2 emissions had been decided many years ago.
"The fact they are reviewing it after the project is done, after $40 billion was invested, is a real attack on the state's sovereign risk," he told reporters on Tuesday.
The former Barnett government originally approved the LNG plant in 2011, under the condition it contributed $13 million in environmental offsets and carbon offsets of about 2.6 million tonnes per year of reservoir carbon dioxide emissions.
However, the carbon offset was waived in 2013 after Chevron objected that any state conditions would be over-ruled if Commonwealth greenhouse gas arrangements came into effect.
Conservation Council of WA director Piers Verstegen said the review would help boost jobs through investment in carbon farming and other technologies.
The Wheatstone project was commissioned in October. When fully operational, the plant is expected to emit up to 10.4 million tonnes of CO2 per year.
"(That) accounts for nearly 12 per cent of WA's total carbon pollution," Mr Verstegen said.
The Opposition spokesperson for Environment Steve Thomas has accused the environment minister of trying to sneak the review through.
"His failure to make any public comments explaining the rationale for this review, which has the potential for significant ramifications throughout the mining and resources sector, is alarming," Dr Thomas said.
Mr Dawson has been sought for comment.