The low-cost airline Norwegian on Thursday announced long-haul routes between Scandinavia, New York and Bangkok, putting further pressure on troubled rival SAS.
The move was considered unusual because reducing prices on long-haul flights is said to be harder than cutting fares on short-haul routes.
As it begins to take delivery of eight new Boeing 787 Dreamliners, Norwegian will begin flying between the Swedish and Norwegian capitals and New York at the end of May next year, and to Bangkok at the beginning of June.
Stockholm and Oslo will each have three weekly departures to the new destinations.
Norwegian cranked up its offensive against traditional carriers in January by announcing an order for 222 Boeings and Airbus, with additional purchase rights for 150 aircraft from both manufacturers.
The airline said it was Europe's largest plane purchase ever.
Europe's third largest low-cost airline after Ryanair and easyJet has proved to be a formidable challenger to SAS, which on Thursday delayed the release of its quarterly results as it scrambles to complete a restructuring plan.