Finland’s flag-carrier airline, Finnair, said it has been forced to cancel almost 300 flights amid a nationwide solidarity strike for postal workers.

The carrier, whose home airport at Helsinki acts as a major hub for Europe-Asia connections, said around 20,000 passengers would be affected by Monday’s action.

It comes after the Finnish airport workers’ union joined a solidarity strike on behalf of 9,000 employees at the publicly-owned postal service Posti, who have been on a two-week strike against pay cuts.

Finland’s chief labour conciliator, Vuokko Piekkala, said on Sunday attempts to forge an agreement in the dispute had failed, after extensive negotiations over the weekend.

Finnair spokeswoman Paivyt Tallqvist said: “Our current estimate is that we could operate some 120 of our 377 flights scheduled for tomorrow.”

The solidarity strikes were expected to largely stall public bus transport in Finland’s capital Helsinki on Monday, while the Finnish Seafarers’ Union said it would stop all passenger and cargo vessels flying the Finnish flag in Finnish ports starting on Monday until further notice.

The strike has also led to mail deliveries being interrupted in Finland ahead of the busy Christmas season.

Apart from the postal strike, there might be more widespread strikes on the way, potentially affecting other Finnish industries, as three other employee unions called at least 85,000 workers to join a three-day strike starting December 9 in separate wage disputes.