Two people are in police custody after occupying an offshore Woodside gas platform about 200 kilometres off Western Australia's coast to protest against the company's gas operations.

An Australian Border Force (ABF) spokesperson said they were working with federal and state agencies to respond to the situation after activists occupied the rig overnight and disrupted the gas giant's operations.

Images shared by environmental advocacy group Greenpeace Australia Pacific show its activists scaling a Woodside gas platform and hanging a banner in protest of the company's planned gas project at Scott Reef.

Greenpeace said four protesters travelled to the platform early Saturday morning, and two of them set up "temporary hanging tents" to occupy the platform for "as long as possible".

On Sunday afternoon Greenpeace said two of its activists had been taken into police custody.

"Special police forces landed a helicopter on the [platform] at around 11:30am AWST," Greenpeace said.

"The activists safely removed themselves from their equipment before being taken into police custody around 1pm."

Woodside confirmed the protest had disrupted operations at the rig, which forms part of the company's $12.5 billion Scarborough natural gas project.

"Pre-commissioning activities at Scarborough have been paused as part of routine procedures following the unauthorised access," a spokesperson said.

Scott Reef is Australia's largest standalone oceanic reef and a refuge for thousands of aquatic creatures and shorebirds — Woodside's plans have been heavily contested by environmental groups opposed to gas developments in the area.

Woodside's Browse gas project plans to tap into Australia's largest undeveloped offshore gas reserve, and is estimated to cost about $48.7 billion according to a Deloitte analysis.

Woodside said Greenpeace's activists had "deliberately and unlawfully" accessed the floating production unit and had "not only endangered their own safety, but that of Woodside staff".

"Greenpeace's actions have triggered a significant, potentially costly and entirely avoidable response, requiring Western Australian resources to be mobilised to manage the safety, security and operational consequences of their actions," a Woodside spokesperson said.

"The activists' conduct is not peaceful. It is dangerous, reckless and illegal."

Greenpeace Australia Pacific CEO David Ritter said the activists involved in the latest demonstration were "highly trained and experienced", and said care was "always taken in the health, safety and welfare of all involved".

He said environmental groups had been scaling up their activism in response to Woodside's planned Browse project.

"Greenpeace and other community organisations have been building up their activities matching that rise in community concern," Mr Ritter told the ABC.

"There is no question that our activities are increasing to match this reckless threat of Woodside."

'Reckless behaviour': Minister

Federal Resources Minister Madeleine King said the activists had broken several laws, and described the protest as "reckless behaviour in the extreme".

"Putting so many lives at risk all for a 20-second TikTok ... we expect the authorities once they've done their proper processes to throw the book at them," Ms King said.

WA Greens fossil fuels and climate change spokesperson Sophie McNeill rejected Ms King's comments.

"The real selfish ones putting lives at risk is Woodside — not these Greenpeace activists — as the fossil fuel giant recklessly opens massive new gas projects in the middle of a worsening and increasingly deadly climate crisis," she said.