The siege began at 09:00 on Saturday.
The activists announced in a press release that eight kayaks and three motorboats entered the safety zone to prevent the normal operation of the tankers.
The facility at Kärstö is the largest of its kind in Europe. It receives gas from Asgard and other fields in the Norwegian Sea.
This would be Thunberg's first action against Norwegian oil and gas.
“We cannot watch silently as they destabilize our biosphere and our life-support systems, and thus act in a way that causes people to die,” she says.
Previously arrested
Greta Thunberg has appeared several times in the past year in connection with Extinction Rebellion protests. In early July, she was arrested in The Hague, Netherlands, and in late June, she was taken by police in Helsinki.
“One could ask who is committing the real crime. Are they the ones who are destroying our chances for a secure future and causing people to suffer the consequences of the climate crisis already today – or are we the ones who are trying to stop this development?” says Greta Thunberg.
The protests stir strong emotions. Thunberg says the key to moving forward is communication.
– We must not leave people behind in this urgent transformation. Everyone must participate on their own terms. That is why it is important that we start as soon as possible, because the longer we wait, the more radical the change will be.
“Falls down a lot. Internet fanatic. Proud analyst. Creator. Wannabe music lover. Introvert. Tv aficionado.”
More Stories
More than 100 Republicans rule: Trump is unfit | World
Botkyrka Municipality suspends its directors after high-profile trip to New York
Huge asteroid approaching Earth | World