Thousands of security workers at Heathrow Airport are to strike over the summer.
A further three months’ industrial action will go ahead in an ongoing dispute over pay, the Unite union has confirmed.
The strikes will involve more than 2,000 members of security staff at the west London airport, and are pencilled in to begin in mid-June and run until August bank holiday.
The number of strike days and their exact dates has not been confirmed, although Unite has said it could run to more than 30 days - a serious escalation of the strikes that by the same workers at the airport in recent months.
Security personnel represented by Unite working in Heathrow Terminal 3 and Terminal 5, are expected to join the walkouts after they rejected an updated pay offer from the airport.
British Airways flights leaving from Terminal 5 could be affected, while airlines using Terminal 3 including Virgin Atlantic, Emirates, Qatar Airways, United, American Airlines and Delta Air Lines may see their service suffer.
A Heathrow spokesperson said: "Passengers can rest assured that we will do everything we can to minimise strike disruption so they can enjoy their hard-earned summer holidays.
"Unite has already tried and failed to disrupt the airport with unnecessary strikes on some of our busiest days and we continue to build our plans to protect journeys during any future action.
"The simple fact remains that the majority of colleagues do not support Unite's strikes. There is a two-year inflation-beating pay rise ready for colleagues, if only Unite would allow them to have a say. We will continue talks with Unite about resolving this issue."
Although the strike dates are not confirmed, workers could be set to walk out across dates in June, July and August, coinciding with the school holidays.
Unite general secretary Sharon Graham “Unite is putting Heathrow on notice that strike action at the airport will continue until it makes a fair pay offer to its workers.
"Make no mistake, our members will receive the union’s unflinching support in this dispute. HAL has got its priorities all wrong.
"This is an incredibly wealthy company, which this summer is anticipating bumper profits and an executive pay bonanza.
"It’s also expected to pay out huge dividends to shareholders, yet its workers can barely make ends and are paid far less than workers at other airports."
The strike is a major escalation both in terms of the number of days of industrial action, as well as the workers involved.
For the first time security officers based at Terminal 3 will take part, joining their colleagues from Terminal 5 and campus security - who check vehicles and personnel in the airport - on the picket line.
