The industrial action is happening at the height of the tourist season.
Travellers to Portugal are being warned to expect delays amid a planned strike by border control staff.
The UK’s Foreign Office has told people heading to the country to allow additional time to get through immigration controls.
The strike is set to take place on Thursday, August 24 and Friday, August 25.
Airline easyJet has told customers that it expects to fly its planned programme in full, to and from Portugal.
It has told its travellers leaving Portugal on these days to arrive at the airport two hours earlier.