Saturday night's negotiations yielded no concrete results and the airline and unions remained some distance apart on Sunday.
Both sides claimed to have "made real attempts to find a way out of the frozen conflict" and Norwegian's management said that the company has budged a fair way in its negotiating position.
"There are ongoing negotiations and that's all I can say," said Norwegian's communications head Charlotte Holmbergh Jacobsson to news agency TT on Sunday morning.
The airline announced that almost all domestic flights in Sweden and Norway, as well as a limited number in Denmark, were to be cancelled on Sunday. Passengers have been urged to check the airline's website to confirm the status of their flight.
Meanwhile the Finnish aviation trade union IAU announced a 14 hour sympathy strike, which has meant cancelled and delayed flights from Helsinki. According to news agency FNB, Norwegian considers the strike illegal and has warned IAU over the economic consequences.
As the bitter stand off entered its ninth day, Norwegian estimated that a total of 130,000 passengers had to date been affected by the strike and the estimated cost has exceeded 100 million kronor ($12 million). The exact amount remained unclear, but experts estimate that the cost is climbing by tens of millions kronor each day.
The conflict stems from a demand from the pilots to sign a collective agreement directly with the parent company Norwegian Air Shuttle, NAS, instead of its subsidiary, Norwegian Air Norway, NAN, where they are employed.
The demand is considered by the company to be completely unreasonable and during the conflict the pilots have been transferred into three newly formed subsidiaries: Pilot Services Norway, Denmark and Sweden.