Lufthansa faces strike action by thousands of workers on Monday to increase pressure on management in pay negotiations.

The Verdi union, representing about 33,000 employees, described a pay offer put forward by the airline’s management on Wednesday as “scandalous” and said that it would represent a drop in pay in real terms over the next 12 months.

Staff held a one-day strike on March 21, forcing Lufthansa to cancel nearly 40% of its flights.

Lufthansa’s offer was to raise salaries by 1.2% from October and a further 0.5% a year later, in a deal that would run for 29 months and would not contain job guarantees.

Verdi is demanding a 5.2% pay rise for cabin crew and ground staff at Lufthansa Cargo, Lufthansa Technik, Lufthansa Systems, catering unit LSG Sky Chefs and ground crews. It also wants a commitment by Lufthansa to safeguard jobs.

The call for industrial action was for full-day strikes at Frankfurt, Europe’s third-largest airport, as well as Munich, Hamburg, Stuttgart, Hanover, Dusseldorf, Cologne and Norderstedt, Reuters reported.

Workers have been asked to strike during the morning in Nuremberg and until 8.30am in Berlin.

Lufthansa said it was too early to predict the exact impact on Monday’s flight schedule but confirmed that there would be delays and cancellations.

The two sides have already agreed on April 29-30 and June 2-3 as dates for further pay talks.