Greek civil aviation workers plan a five-day strike next week in protest at the long-term lease of 14 regional airports, complicating government efforts to implement a privatization program linked to the country’s bailout.

Authorities agreed to lease the airports to German operator Fraport last year and are now considering offering concessions for 23 others.

The walkout, called by civil aviation workers union OSYPA from June 20-25, is expected to disrupt domestic and international flights as airports will operate with emergency staff only.

Privatizations have been a key element of the three international bailouts Greece has received since 2010, but they have reaped very limited revenues due to political resistance, bureaucracy and opposition by unions.

Port workers have been on 48-hour rolling strikes since late May to protest the sale of Greece’s two largest ports in Piraeus and in the northern Greek city of Thessaloniki.

Workers at state railways operator Trainose have also been staging stoppages against its privatization, and are expected to hold a 24-hour strike on June 22, when final bids from investors are due.

Under a third international bailout the left-led government signed up to a year ago, Athens has promised to conclude a series of pending deals and set up a new umbrella privatization fund by September which will include additional state assets.

The $1.35 billion deal with Fraport and its Greek partner, energy group Copelouzos, covers the operation of 14 provincial airports in popular tourist islands including Corfu and Santorini.

The German firm is expected to start operating those airports by the end of this year, once it gets pending approvals and technical issues are ironed out.

Privatization agency HRADF published an invitation on Monday to hire an advisor to work out whether another 23 regional airports can be further developed.

OSYPA is concerned that such a move would result in job losses, further hurting an already struggling economy.

“The privatization agency proceeds with the sell-off of the remaining… regional airports aiming, as its charter stipulates, to shut the ones that will not be sold,” the union, which represents about 1,200 workers, said in a statement. “We really wonder whether politicians and local communities have realized what the closure(s) …will mean.”

HRADF said the invitation is just part of a preparation process before the 23 airports are transferred to the new fund in September.