Finnair has announced that approximately 110 of its flights on Friday would be cancelled, due to industrial action.
The situation affects around 8,000 of the airline's customers.
The flag carrier has said it is notifying affected passengers personally, by email or SMS.
According to Nina Pärssinen from the National Mediator's office, the Finnish Aviation Union IAU and employers' group Palta have failed to reach an agreement on collective bargaining talks.
As a result, the IAU said that previously announced work stoppages are going ahead. The four-hour industrial actions are set to take place on Friday 30 May, Monday 2 June, and Wednesday 4 June.
The IAU also issued a new strike warning for Wednesday June 11.
Flag carrier Finnair said it was assessing how the work stoppages could affect its flights, and so far has cancelled around 110 flights on Friday.
The airline and unions have been deadlocked in negotiations since late January, a period which has seen hundreds of flights cancelled, affecting thousands of passengers.
The IAU said that it rejected an agreement proposal made by the mediator on Tuesday. According to the union, the main dispute between the parties concerns salary levels.
It said that due to salary increases that were not implemented in 2021 and 2022, the aviation sector has fallen behind others in terms of remuneration. The union said that this factor must be taken into consideration.
According to the IAU, average annual earnings of Finnair Group's employees last year amounted to just over 70,000 euros. Compared to 2020, the employees' earnings increased by 6.4 percent, the IAU said.
However, due to savings measures that were agreed to during Covid and Russia's invasion of Ukraine, the salary increases fell short of the general 10.4 percent salary increases during that four-year period, the IAU noted in a media release that was updated on Wednesday.
According to the employers' group Palta, the majority of personnel groups were prepared to accept proposed salary increases, but said the IAU still seeks bigger raises.
Members of the IAU take care of aviation passenger-, ground handling- and cargo services.
