The environmental group says it is 'one of the biggest legal threats' in history against its ability to campaign.
Shell is suing Greenpeace for millions in damages after activists boarded the company's oil production vessel in transit at sea this year.
The British oil and gas major filed the claim against the environmental group in London's High Court.
Greenpeace says the "intimidation lawsuit" demands that they stop protests at Shell's infrastructure at sea or in port anywhere in the world, forever, or face a potential €8 million damages claim and an injunction.
It is one of the "biggest legal threats" ever against the environmental organisation's ability to campaign, it adds, and a bid to "silence growing dissent" over Shell's plans to double down on fossil fuel investment.
Why is Shell suing Greenpeace?
In an email to news agency Reuters, Shell confirmed legal proceedings were taking place when asked whether it was suing Greenpeace over the incident but declined to comment on the claim amounts.
Greenpeace says the oil major has told them in correspondence that the damaged would be around €8 million. But Reuters reports that the NGO is being sued for €2 million.
Boarding a moving vessel at sea was "unlawful and extremely dangerous", a Shell spokesperson said.
"The right to protest is fundamental and we respect it absolutely. But it must be done safely and lawfully," they added.
How did Greenpeace activists board an oil vessel?
Greenpeace activists boarded the moving oil platform in January near the Canary Islands off the Atlantic coast of northern Africa. They travelled on it as far as Norway to protest the climate damaged caused by Shell's oil drilling.
The vessel was destined for the Penguins oil and gas field in the North Sea, which is not yet in production.
Four Greenpeace activists used ropes to hoist themselves onto the vessel from inflatable boats that chased the ship at high speed. A total of six activists occupied the vessel for 13 days in January and February this year.
Protests at sea against oil, gas or mining infrastructure have long been part of Greenpeace's operations.
One of the 'biggest legal threats' against Greenpeace
The damages Shell is seeking include costs related to shipping delays and expenses for extra security, as well as legal costs, according to a document seen by Reuters.
"The claim is one of the biggest legal threats against the Greenpeace network’s ability to campaign in the organisation’s more than 50-year history," Greenpeace said in a statement.
The group said Shell offered to reduce its damage claim to €1.3 million if Greenpeace's activists agree not to protest again at any of Shell's oil and gas infrastructure at sea or in port.
Greenpeace said it would only do so if Shell complied with a 2021 Dutch court order to cut its emissions by 45 per cent by 2030, which Shell has appealed.
A claim for additional damages of around €6 million by one of Shell's contractors, Fluor, is unresolved, according to the document seen by Reuters. Fluor did not immediately respond to a request for comment.
Shell and Greenpeace have held negotiations since the case was filed, but talks ended in early November, Greenpeace said, adding it was now waiting for Shell to file further documents in court.
Greenpeace said it will then consider its next steps, including ways to stop the case from proceeding.
'I have lived through the devastation caused by Shell'
Among those who attempted to board the oil vessel was Yeb Saño, the executive director of Greenpeace Southeast Asia.
“I have lived through the devastation caused by Shell and companies like them," says Saño, who is named in Shell's legal claim. "10 years ago I spoke at COP global climate talks while my brother was still missing in the fall-out from Super Typhoon Haiyan. Incredibly, he survived, but he helped carry the bodies of 78 innocent people who tragically did not."
He says he took part in the protest to demand that Shell "stop its senseless and greedy pursuit of fossil fuels and take accountability for the destruction it is wreaking upon the world.
"If Shell refuses to stop drilling, I refuse to stop fighting for climate justice,” he adds.