"As I understand it, the fire is in a cargo building away from the main airport and we do not expect any impact on flights from Arlanda," said Anders Bredfell at Arlanda Airport to The Local on Friday afternoon.
The airport has confirmed that the fire, which broke out at around lunchtime on Friday, is located in a cargo area within the airport.
"The smoke near Heathrow is coming from a fire in a nearby cargo area. The fire service are in attendance, no impact on terminals or flights," according to the latest post on the airport's Twitter feed.
The fire is described as major and according to the UK Sky News, plumes of smoke can be seen from "at least 6 miles away (9.65 kilometres) away."
Around 100 firefighters are at the scene, according to a Reuters report.
Before signing off for the weekend, a Heathrow tweet informed that the airport was operating as normal and the fire, while still raging, had been brought under control.