Icelandair Group carried 120,000 international passengers in December, an increase of 20% year-on-year.
Capacity on international routes rose by 27%, while load factor fell by 1.6 percentage points to 72.7%.
Passenger numbers on regional services and flights to Greenland - which are served by group subsidiary Air Iceland - fell 9% to 22,000 against a capacity decline of 14%.
Regional load factor grew by 3.6 percentage points to 66.5%.
In the cargo business, FTK throughput for the group decreased by 2% against a capacity increase of 7%.