Ground and cabin staff at German carrier Lufthansa will go on strike from Monday, causing travel chaos at the very height of the summer holidays. The walkout is the second industrial action Europe's second biggest airline is facing in days after pilots at two of the airline's subsidiaries held a one-a-half day walkout earlier this week.

The latest strike, which will run indefinitely, will start from midnight on Sunday. The walkouts will be staggered at different airports and are likely to cause major disruption to Lufthansa flights.

German services union Ver.di, which represents around 52,000 Lufthansa workers, announced the walkout at a press conference in Berlin on Friday. The union's head Erhard Ott told reporters the mood among staff was "explosive."

Nearly 91 percent of its Lufthansa members had backed the strike, Ott said, which is over pay: The union is demanding a 9.8 percent pay rise for its members over the next year, while Lufthansa has offered an increase of 6.7 percent in two steps and a one-off payment.

According to a report in Friday's edition of the Rheinische Post newspaper, Lufthansa has drawn up a detailed emergency plan to safeguard around 75 percent of flights during a strike lasting several weeks. A company spokeswoman refused to comment on the report on Friday, the Associated Press reported, saying only that Lufthansa was making preparations for a walkout.

Ver.di's chief negotiator Ott said the strike would cause "considerable" disruption to flights. But he asked passengers for understanding, as he said industrial action was necessary because four rounds of negotiation had achieved nothing.

Earlier this week Lufthansa subsidiary airlines Eurowings and Cityline had been hit by a separate strike when airline pilots' union Cockpit had staged a one-and-a-half day walkout , which led to nearly 1,000 flights being axed.

Lufthansa is by no means the only German company to have been facing far higher wage demands, sparked by rising inflation, which stood at 3.3 percent in June. Already this year, unions secured a 5.2 percent wage increase for steelworkers and a 4.4 percent rise for workers in the chemicals industry. The pay rises were some of the biggest hikes in wages in Germany since the mid-1990s.