Last-minute efforts by Germany's largest airline to halt the strike failed after a court in Frankfurt on Wednesday confirmed that the walkout was legal 

Tens of thousands of Lufthansa passengers faced disruptions Thursday as cabin crew in Germany staged a "massive" 48-hour walkout in the biggest escalation yet of a bitter row over pay and conditions.

The strike called by Germany's UFO flight attendants' union started at 2300 GMT on Wednesday and was to last until 2300 GMT on Friday.

Lufthansa said it had scrapped 700 flights on Thursday and some 600 the following day, warning that "around 180,000 passengers will be affected" across Germany.

The UFO union argued that the stoppage was necessary because negotiations with Lufthansa bosses were deadlocked.

But it accepted a surprise olive branch offered by Lufthansa CEO Carsten Spohr on Thursday, and agreed to preliminary talks over the weekend.

The current strike would carry on as planned "but would not for now be expanded", UFO said on its website.

Lufthansa said it regretted the inconvenience to passengers and stressed that it was working "to minimise the impact of this massive strike on our customers".

The carrier was running an alternative flight schedule where possible, and said passengers could rebook their journeys for free or swap their flights for train tickets.

Knut Kress, a passenger at a quieter than usual Munich airport, voiced support for the flight attendants.

"It's good that there are still unions defending something," he told AFP. But 48 hours "is a long time", he added.

Fellow traveller Birgit Kellner complained about the lack of notice for passengers.

"They should inform passengers a little earlier, not just two days before."

The walkout is UFO's biggest call to action since a week-long strike in 2015 hit Lufthansa with mass cancellations.

It is also seen as a test of strength for the union, weakened by months of infighting that have left Lufthansa questioning its right to speak for cabin crew.

Internal disputes

Lufthansa's finance chief Ulrik Svensson declined to put a price tag on the strike but said such stoppages typically cost "between 10 and 20 million" euros per day.

The union already staged a day-long warning strike last month at four Lufthansa subsidiary airlines, causing several dozen flights to be axed at Eurowings, Germanwings, SunExpress and Lufthansa CityLine.

But the flagship Lufthansa brand was spared the upheaval after management offered an unexpected two-percent pay rise to avert the strike.

Since then, however, UFO vice-president Daniel Flohr said no progress had been made in talks.

As well as higher pay for cabin crew across the Lufthansa group, UFO is demanding more benefits and easier routes into long-term contracts for temporary workers.

Lufthansa, however, has long argued that UFO no longer has the right to represent its staff following an internal leadership tussle, and has challenged the union's legal status in court.

But CEO Spohr hinted at a shift in position when he told reporters Thursday Lufthansa wanted to try to resolve the existing legal issues with UFO in the weekend meeting, hoping to then start formal arbitration talks.

UFO's internal disputes have cost it support among the Lufthansa group's 21,000 flight attendants, with some members switching to rival unions.

Separately on Thursday, Lufthansa reported a jump in third-quarter net profits but said it was slashing over 700 jobs at its Austrian Airlines subsidiary as the group seeks to trim costs in the face of fierce competition.