The environmental campaign group says the action, being brought by Shell and a contractor, is an "intimidation" suit.

The case, filed at the High Court in London, relates to a climate protest that began in January this year aboard one of Shell's oil platforms while it was in the Atlantic, off the Canary Islands, in transit to the North Sea.

Four activists used a boat to board the vessel and protesters remained with it until the platform reached a Norwegian port.

According to Greenpeace, Shell was seeking £1.7m in damages but had offered to reduce its claim to £1.1m in return for campaigners agreeing not to protest again at any of Shell's oil and gas infrastructure at sea or in port.

The other company involved in the action is Fluor, an American oil and gas services provider.

Documents seen by Sky News suggested that it was seeking damages from Greenpeace of £5.3m.

Shell, which did not comment on the amount it was seeking, cited additional costs from shipping delays and security.

The company, which had announced record annual profits of £32bn while the protest was taking place, said in a statement that boarding a moving vessel at sea was "unlawful and extremely dangerous".

The spokesperson added: "The right to protest is fundamental and we respect it absolutely. But it must be done safely and lawfully."

Greenpeace, which described the legal action as among the biggest legal threats it has faced in its 50-year existence, said it would only comply with Shell's offer to reduce its damages claim if the company complied with a
2021 Dutch court order to cut its emissions by 45% by 2030 - a ruling that Shell has appealed.

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Areeba Hamid, co-executive director of Greenpeace UK, said Shell's leadership was "trying to crush Greenpeace's ability to campaign, and in doing so, seeking to silence legitimate demands for climate justice and payment for loss and damage".

She added: "We need this case to be thrown out and for Shell to be regulated by the government."