Ryanair threatened by fresh strikes in Germany
Ryanair's German pilots have voted overwhelmingly in favour of striking in a row over pay and conditions.
The Vereinigung Cockpit pilot union said 96% were in favour of striking.
It has given Ryanair until 6 August to make an offer to avoid a strike, which must be announced 24 hours in advance.
Ryanair has already cancelled hundreds of flights this month due to pilot strikes in Dublin and cabin crew walkouts in Italy, Spain, Portugal and Belgium.
The Vereinigung Cockpit pilot union said discussions with Ryanair last Friday had failed to secure the progress it wanted.
It wants collective bargaining agreements with Ryanair and conditions on a par with similar budget airlines such as TUI.
Ingolf Schumacher, chairman of collective bargaining agreements at Vereinigung Cockpit (VC), accused Ryanair of "playing in the negotiations" which have been going on since January.
Ryanair said it had invited the union to another meeting next week.
"We hope we can make further progress in concluding a collective labour agreement with our pilots in Germany," a spokesperson for the airline said.
News of the potential strikes in Germany came as Ryanair invited Irish pilot union Forsa to talks after last week's strikes and ahead of a potential fresh day of strikes on Friday 3 August.
The low-fare airline has already cancelled 20 of 300 flights due to take off on Friday, when a quarter of Irish pilots are due to walk out.
The 3,500 customers affected have already been re-accommodated or refunded.
Ryanair said it had already agreed to nine of Forsa's 11 requests.
"The 20 cancelled flights next Friday cannot be recovered even if this unnecessary (fourth) strike is called off.
"We hope Forsa will accept our invitation to meet either next Saturday (4th) or any day the following week commencing Mon 6 Aug," Ryanair's chief operating officer Peter Bellew said.
Ryanair agreed last year to recognise unions as official representatives for workers, but it has struggled to reach agreements with some of them.The move followed a scheduling crisis last September which led to the cancellation of thousands of flights.