Ground employees of German airline Lufthansa went on strike at major airports across the country on Tuesday for the second time this month, adding to the tension in ongoing wage negotiations scheduled to resume on Wednesday.

"If Lufthansa does not realize that it now has to take a big step towards us, then longer strikes will continue to be possible," labor union Verdi's lead negotiator, Marvin Reschinsky, said.

Over 100,000 passengers will be affected by the industrial action, which is due to run until 7:10 a.m. local time (6:10 a.m. GMT) on Wednesday, the airline has said.

Lufthansa said it could only operate 10% of scheduled flights at the affected airports, which include the country's biggest hub in Frankfurt as well as Munich, Hamburg, Berlin, Duesseldorf, Cologne and Stuttgart.

The first flights were canceled on Monday evening.

Germany, Europe's largest economy, has been hit with several nationwide strikes affecting air travel, railways and public transport, as workers faced with high inflation demand greater pay.

"The strikes in Germany are pretty annoying at the moment," Martin Pilo, who had just arrived from Singapore but was waiting on luggage, said while standing in one of Frankfurt's terminals, where most Lufthansa check-in counters remained closed.

The latest strike at Lufthansa comes after the airline presented a new wage offer for some 25,000 ground staff workers last week. Verdi described the offer as "blatantly antisocial."

Verdi is demanding a wage rise of 12.5% or at least 500 euros ($538.85) more per month over 12 months, plus a one-time payment of 3,000 euros to offset inflation.

These high demands have become necessary as Lufthansa's ground staff has lost 10% of its purchasing power in comparison to 2021, Verdi's Reschinsky said.