Some 64 flights were cancelled at Geneva’s international airport on Friday, it said, after operations were halted for four hours because of a strike by workers at the start of the busy summer travel season.

“Because of the social action… the direction decided a temporary halt of operations from 6:00 am to 10:00 am (0400 GMT and 0800 GMT),” the airport said in a tweet early on Friday. “64 flights — arrivals and departures — cancelled.”

An airport spokesman said on Thursday that some 8,000 passengers were estimated to be affected by the cancellations at Switzerland’s second airport, a key hub for the EasyJet budget carrier. Numerous international flights from North America and the Middle East were affected.

The strike was called after the airport’s board approved on Thursday a new wage policy contested by staff, and could be renewed for the days ahead.

Many police and security staff were posted in front of the terminal and only passengers for flights scheduled for after the strike period were being allowed inside.

About 50 striking workers and trade unionists were protesting outside the terminal’s main entrance.

It is the first-ever strike by staff directly employed by the airport, as opposed to subcontractors, and according to Swiss airline includes air traffic controllers as well as those which guide planes along the tarmac. A trade unionist said it was difficult to understand how they had arrived at the impasse.

“The airport is a profitable business which enjoys a monopoly and is attacking the conditions of its staff,” said Pierre-Yves Maillard, head of the Swiss Trade Union Confederation (USS), who turned out to support the strikers.