Environmental campaigners are threatening to shut down every Shell petrol station in Edinburgh in a protest against the company's plans to drill in the Arctic region.
Greenpeace said they intended to close about a dozen stations across the capital.
One of the first to be targeted was in Dalry Road, in the west of the city.
Shell said it recognised the right of individuals to express their point of view.
Activists said they were using the emergency shut-off switch, which stops petrol going to the pumps, to close the stations.
They also draped a large banner showing images of animals Greenpeace believes are threatened by oil exploration in the Arctic, and used tape carrying the slogan Save the Arctic to close access to the station.
Protesters could be seen on the roof of the Shell station in Dalry Road early on Monday morning, and a man in a polar bear outfit chained himself to a pump before being cut free and led away by police.
Greenpeace also claimed to have shut the Maybury Shell station in Edinburgh, and said five of its activists had been arrested in the city by 09:00.
The protesters said they planned to spend the rest of the day touring the city using a combination of low-emission cars, bikes and public transport while shutting off the petrol supply to other Shell pumps.
Greenpeace also said it would broadcast live video of the protest on its website.
A similar direct action protest is being carried out in London, where Greenpeace activists said they were aiming to shut about 100 Shell stations.
Greenpeace's Sara Ayech said: "The oil giant Shell is preparing, for the first time, to unleash a drilling fleet of huge vessels upon the fragile and beautiful Arctic, home of the polar bears.
"It's time to draw a line in the ice and tell Shell to stop. That's why today we're going to shut down all of Shell's petrol stations in the capital cities of London and Edinburgh. We've got dozens of people who will hit over 100 Shell garages throughout the day.
"An oil spill in the Arctic would be catastrophic for wildlife such as walruses and whales, and Shell knows full well that it would be impossible to clean up after such devastation. The Arctic must be saved, and made a global sanctuary where oil drilling is banned."
The protest comes after more than a dozen people were detained as Greenpeace activists blocked access to Shell's headquarters in The Hague in the Netherlands on Friday.
A spokesman for Shell said: "Shell recognises that certain organisations are opposed to our exploration programme offshore Alaska, and we respect the right of individuals and organisations to engage in a free and frank exchange of views about our operations.
"Recognising the right of individuals to express their point of view, we only ask that they do so with their safety and the safety of others, including the general public and Shell personnel in mind.
"Shell has met with numerous organisations and individuals who oppose drilling offshore Alaska. We respect their views and value the dialogue. We have extended this same offer for productive dialogue to Greenpeace."
Greenpeace launched a Save The Arctic campaign last month to preserve the land mass from oil exploration and industrial fishing.
The group has called for an agreement to ban environmentally damaging activities in the Arctic region, just as they were banned in the Antarctic 21 years ago under a protocol added to the Antarctic Treaty.
In May, the Greenpeace's activists temporarily halted several icebreakers heading for the Arctic in a bid to block Shell's plans to drill for oil in the region.
And last month the environmental group called for more use of renewable energy and greener cars in what it said would help protect the Arctic and other areas from being spoiled by oil drilling.
According to the US Geological Survey, the Arctic is believed to hold 13% of the planet's undiscovered oil reserves and 30% of its undiscovered natural gas.