The SNPVAC union, which represents civil aviation flight personnel, has pledged to join the general strike on Wednesday (3 June). Its president Ricardo Penarroias told Portugal's Jornal de Negocios the action by its members could affect up to 500 flights.

The action will primarily affect Portugal's national carrier Tap, although easyJet said it expected "some disruption" to its flying programme. Ryanair, by contrast, told The Independent it doesn't expect any disruption to its schedule and would operate as normal.

Tap said passengers with tickets issued by 20 May for travel on 3 June can bring their bookings forward, for free, for flights operating before 2 June, or postpone their travel to dates between 4 June and 11 June, again, for free.

Sata Air Acores and Azores Airlines, which serve Portugal's Atlantic islands after which the carriers are named, said service may be "constrained" owing to the strike and is allowing passengers to change their trips, free of charge, to alternative flights operating between 1 June and 7 June.

The general strike has been called by Portugal's largest union, CGTP, as part of a dispute over labour law reforms. Portugal's pilots' union SPAC has opted not to join the latest round of action, but told national media in Portugal it did not believe the reforms went far enough.