The trade union Fórsa has said its Irish-based Ryanair pilots will stage a further one-day strike this month.
It will take place at 1.00am on Friday August 10th, and will be the fifth one-day strike by directly-employed Irish-based Ryanair pilots since July 12th.
Ryanair has said this will affect "just 25%" of its Irish pilots.
The strike ties in with notice of action by pilots in Sweden and Belgium on the same day.
On Wednesday, the Swedish Airline Pilots Association (SweALPA) said it called the action because the airline had consistently refused to meet with its representatives without preconditions.
Belgian pilots, meanwhile, accused Ryanair of 'unacceptable' practices that "go against the right to strike, which is a fundamental right guaranteed by all international conventions".
In a statement, the airline said pilots in Germany and the Netherlands could also down tools on the same day.
In a statement outlining the latest Irish action, Fórsa said: "For over a month, the union has said that industrial action is likely to continue until there is substantial movement on the pilots' reasonable demands for an agreement on a fair and transparent approach to base transfers and related matters.
"In the 19 days since the first one-day strike took place, company management has agreed to just two hours of talks, despite Fórsa's repeated assurance that it is available for discussions at any time.
"The union has today told Ryanair that it remains available for talks."
It claimed the airline's "escalation" of the dispute last Wednesday - when it issued protective notice to 300 of its staff, or offered a transfer to Poland - led to "a predictable hardening of resolve among its staff".
Company management met the union the day before the first one-day strike on July 11th, and two days before the second one-day strike on July 18th.
Fórsa said three weeks will have passed by August 11th since the last meeting between the parties.
Ryanair earlier said it asked Fórsa to meet them on August 7th, which Fórsa did not address in its statement on Thursday.
Ryanair today (Thurs August 2) asks FORSA to confirm they will meet us at 11am on August 7. https://t.co/ZAZMVweLpe
— Ryanair (@Ryanair) August 2, 2018
Ryanair has said it "deeply regrets" what it called the "unexplained notice" of a fifth strike.
The carrier said Fórsa "again rejected" offers to meet to resolve the dispute on Tuesday August 7th.
Ryanair said in a statement: "Last Monday (30 July) Ryanair invited Fórsa and its Pilot Committee to meet on Saturday 4th August (or early next week) to discuss Fórsa's 11 requirements as a way to resolve this dispute without further customer disruption.
"Ryanair renewed this invitation on Wednesday 1st August and offered to meet Fórsa at Dublin Airport at 11.00am on Tuesday 7th August.
"Rather than accept these invitations to meet (which Fórsa have repeatedly called for), Fórsa have now called a fifth strike for Friday 10th August, which will needlessly disrupt another 3,500 Irish customers."
Ryanair said it will notify affected passengers, to whom they "sincerely apologise", of 20 further flight cancellations for August 10th.
