The parties to the negotiations, the cabin crew union and SAS, were supposed to have responded to the mediators' offer at midnight, but negotiations continued on Wednesday morning.
If either party refuses, the announced strike will go ahead, affecting 640 cabin crew members at SAS.
The impact on air traffic would be significant if the strike goes ahead. But the uncertainty has already led SAS to cancel several flights, including to Stockholm.
The dispute concerns wages and working conditions.
