Greenpeace's ship Rainbow Warrior anchored in Brofjorden outside the Preemraff refinery north of Gothenburg on Thursday evening and stopped a tanker from getting in.
“We are still in Brofjorden, meaning that we are stopping an environmental crime and are stopping all traffic in and out of the fjord,” Isadora Wronski, head of Greenpeace Sweden, told AFP on Friday.
The action is in response to refinery's owner Preem's plans to expand the facility, with the government set to decide on its application for permits.
Dani Backteg, press chief for Preem, said they were in dialogue with authorities but said they had no specific comment on Greenpeace's action.
“Our focus is on maintaining secure production and the security of our employees,” Backteg told AFP.
Greenpeace warned that the proposed expansion would lead to an increase in emissions of up to a million tonnes of carbon dioxide a year, making it impossible to reconcile with Sweden's commitments under the Paris climate accord.
Backteg, however, said the expansion would allow them to produce higher quality products and source renewable fuels, more than offsetting any local increase in emissions.
Part of the expansion will include a facility to refine heavy fuel oil into diesel and gasoline after new regulations from the International Maritime Organization (IMO) on the use of fuel in shipping came into force in January 2020.
In June this year, the Swedish Land and Environment Court of Appeal approved the project but the final decision rests with the government.
“We'll stay as long as necessary and that is when Prime Minister Stefan Löfven intercedes and takes responsibility,” Wronski said.
A spokeswoman for the government declined to comment on the action and said that they could not give a time frame for a decision but said they were actively working on the issue.