The group, from the Tiwi Islands and Larrakia country, insist they didn't give consent for Santos to build the Top End pipeline.

They say the legal challenge could prevent the nation's second-largest independent gas producer borrowing about $1 billion for the Barossa offshore development, putting its financial viability at risk.

Jikilaruwu man Daniel Munkara believes the project would potentially damage pristine sea country and threaten marine life that plays a central role in Tiwi culture.

"Santos did not fully explain their plans to build a gas pipeline along our coast and did not explain any of the risks," he says.

"We were told briefly about the pipeline in 2018 by the previous owners ConocoPhillips and we said no."

Mr Munkara says Santos didn't obtain free, prior and informed consent and the court action is a bid to protect "our family and our land".

"This gas project puts our way of life at risk," he says.

Minister for Northern Australia David Littleproud says while every Australian has the right to undertake legal action, the processes to assess the environmental risks and stakeholders' views did take place.

Santos signed off on the $3.6 billion Barossa offshore development in 2021, making it the largest private economic investment in the territory since Inpex's Ichthys gas project decision in 2012.

It's expected to produce about 3.7 million tonnes of LNG annually and provide valuable export revenue and business opportunities to assist the NT's cash-strapped economy.

It includes a pipeline from the Barossa gas field in the Timor Sea to an existing LNG facility on Darwin Harbour, which is scheduled for an $800 million refit.

The two projects are expected to generate about 600 jobs during construction and another 350 at Darwin LNG over 20 years, with about $2.5 billion in wages and contracts expected to flow into the territory.

Santos says the project is progressing on budget and schedule.

"The Barossa gas project has all the necessary approvals in place," according to a spokeswoman.

"As is the case for all of our projects, we undertake consultation with all key stakeholders where they receive detailed information about the project."

But the Stop Barossa Gas campaign says proposal documents for the project reveal ConocoPhillips sent just two emails and made one unanswered phone call to the Tiwi Land Council during the consultation period for a drilling plan.

It says there was no consultation with Larrakia traditional owners, according to paperwork obtained from the Australian offshore petroleum regulator, NOPSEMA.

Activists have also raised concerns about the pipeline's proposed route through the protected Oceanic Shoals Marine Park and along the entire length of Bathurst Island.

Jikilaruwu man Francisco Babui says construction work, dredging and increased shipping will disturb seabeds and turtle nesting on beaches.

"There is a reef there with lots of turtles and dugongs," he says. "The turtles lay their eggs on that beach and we go hunting in that area."

Larrakia man Kevin Lance Quall says traditional owners do not want more heavy industry in Darwin Harbour.

"The mangrove systems are important to our sea life," he says. "It's where we go to do our hunting, fishing and gathering."

He says the planned route for the pipeline also cuts through the Darramarrangamanidj creator's dreaming track, an important site for the Larrakia people.

Environment Centre NT campaigner Jason Fowler says the project is expected to produce 15.6 million tons of greenhouse gas emissions a year, the equivalent of three million passenger cars.

Lawyers for the groups filed an injunction in the Seoul Central District Court under the Korean Civil Execution Act against the Export-Import Bank of Korea and Korea Trade Insurance Corporation.

Australian Associated Press