An energy giant has vowed to "vigorously defend" its position in two legal challenges sparked by the controversial extension of Australia's biggest gas project near ancient Aboriginal rock art.
Woodside is set to weigh in to the landmark legal battle over the federal government's approval of the North West Shelf gas hub extension until 2070 in Western Australia.
The first legal challenges to September's commonwealth approval have been launched by conservation groups in a bid to overturn the 40-year extension and protect the nearby World Heritage-listed rock art.
The Australian Conservation Foundation has started Federal Court proceedings in Melbourne to challenge Environment Minister Murray Watt's extension approval of the Pilbara project.
Friends of Australian Rock Art has also begun a Federal Court challenge against the minister's decision in a bid to prevent ongoing damage to the Murujuga rock art and other cultural heritage values in the area.
The court challenges are against Senator Watt's decision, driven by concerns the North West Shelf facility will heavily contribute to adverse climate change impacts and harm the 40,000-year-old rock art near the plant.
But Woodside on Monday confirmed it would contest the actions.
"Woodside intends to vigorously defend its position in these proceedings," the company said in a statement.
"The federal government's approval follows a comprehensive and extended assessment carried out by both commonwealth and state regulators in accordance with statutory processes."
The North West Shelf project extension was referred to the federal regulator in November 2018 and was under assessment for nearly seven years, Woodside said.
Australian Conservation Foundation lawyers argue Senator Watt wrongly considered the economic benefits of an unapproved Browse gas project - a separate Woodside proposal to develop a gas field off the Kimberley coast - in his reasons for approving the North West Shelf extension.
They argue the minister gave the green light without knowing the details of the gas the project will process and what pollution it will cause.
Senator Watt also failed to consider the physical effects of climate change as an "impact", the foundation said.
"ACF hasn't made this decision lightly ... despite the risks of litigation we think this is the right time to challenge the minister's decision," the foundation's general counsel Adam Beeson told AAP.
Research released by the foundation in 2024 showed lifetime emissions from the North West Shelf hub would be more than 13 times Australia's annual emissions from all sources, he said.
"We're challenging the lawfulness of Minister Watt's approval of this gas hub extension, which is the centrepiece of the most polluting gas project in the southern hemisphere," Mr Beeson said.
Friends of Australian Rock Art said its challenge was launched on top of its ongoing WA Supreme Court action against the North West Shelf's state approval.
Its lawyers argue the hub extension approval was invalid because the minister failed to properly take into consideration the economic and social harms that would result from ongoing damage to Murujuga heritage.
They said the minister acknowledged the proposal will impact heritage values but considered these impacts were acceptable when the economic benefits claimed by Woodside were taken into consideration.
Friends of Australian Rock Art co-convenor Susan Swain said the Murujuga rock art contained the planet's oldest and most extensive rock art including the earliest recorded depiction of the human face.
"It is pretty disappointing that again, this time at the federal level, we have a decision that looks like it hasn't complied with requirements under the law," she said in a statement.
Senator Watt has been contacted for comment.