Ryanair has cancelled 150 out of a total 400 flights due to fly to and from Germany today due to 24-hour strikes by pilots and cabin crew.

German pilots union Vereinigung Cockpit (VC) has called on Ryanair to agree to mediation in its dispute over pay and terms, but there has been disagreement over who the mediator should be.

Ryanair says its latest offer to VC addressed all of the union’s demands and that the walkouts were unreasonable.

German services union Verdi is seeking a substantial pay rise as well as local contracts for around 1,000 cabin crew at Europe’s largest low cost carrier. It said management had offered local contracts only from 2022.

The airline suffered its worst ever strikes this summer, but secured a breakthrough in August when it reached a deal with Irish pilots and said it was hopeful it could secure deals in other countries soon.

But seven trade unions representing Ryanair cabin crew in Italy, Portugal, Belgium, Spain and the Netherlands last week threatened to hold a strike in late September unless the airline agrees to improve working conditions.

The unions have warned it would be “the biggest strike action the company has ever seen”.

The Irish airline said today’s strikes would “damage Ryanair’s business in Germany” and described them as “unnecessary”.

“These are wildcat strikes designed to cause maximum disruption to our customers and maximum damage to the Ryanair business,” Ryanair’s chief marketing officer Kenny Jacobs told a news conference in Frankfurt.

“It is unacceptable that a union representing Ryanair’s German pilots, who earn up to €190,000 a year and work a five-day week followed by a four-day weekend, is now threatening customers’ travel plans at short notice,” he added.

But British Airline Pilots Association general secretary, Brian Strutton, told the TUC annual congress on Monday: “Ryanair’s own actions during last year were the final straw for many of their pilots, who joined unions across Europe and forged social media groups, to build an underground movement that united and rose up against Ryanair.

“It was not Balpa or other unions, it was the pilots themselves, joining together internationally.

“Saying you will deal with unions is a great step forward but the reality behind that has to be proper, genuine negotiations in line with what the employees want.”

The TUC urged Ryanair to negotiate good quality agreements with unions representing all sections of its workforce in all countries in which it operates. Unite, which represents cabin crew, supported the motion.