Germany's train drivers brought rail traffic to a standstill again early Wednesday as they kicked off their longest strike yet, expected to last six days, to press their demands in a bitter dispute over wages and working hours with the nation's major railway operator.

Piling on travel misery for thousands of passengers, the escalating industrial dispute could cost the economy up to a billion euros ($1.1 billion), economic experts warn.

The strike by the German Train Drivers' Union (GDL) will affect passenger services and freight trains operated by state-owned Deutsche Bahn (DB) until 6 p.m. local time (5 p.m. GMT) on Monday.

Transport Minister Volker Wissing has slammed as "destructive" the six-day industrial action that heaps further pressure on supply chains that are already facing disruption because of attacks by Yemen's Houthi rebels on shipping via the Red Sea.

The prolonged action "is a strike against the German economy," said Deutsche Bahn spokesperson Anja Broeker, noting that cargo traffic handled by the service includes supplies for power plants and refineries.

"DB Cargo will do everything to secure the supply chain, but it's clear that there will be some impact," she added.

With negotiations stalled, the transportation minister said the government was not ruling out arbitration proceedings between GDL and Deutsche Bahn.

"If things are so deadlocked that we obviously can no longer talk to each other, then we urgently need mediation or arbitration," Wissing said on public radio Deutschlandfunk.

The union held a three-day strike earlier this month and two walkouts last year, which lasted up to 24 hours.

On Wednesday, train travel across the country and in many cities ground to a halt again, with commuters and other travelers struggling to find alternatives involving long-distance bus, car travel or flights.

As with the previous strikes, around 80% of long-distance trains were canceled and there were also considerable restrictions on regional services, according to Deutsche Bahn.

There were also considerable restrictions on freight transport.

"European freight traffic across the Alps, Poland or to Scandinavia, as well as the seaports in Holland or Belgium, will also be affected," said Deutsche Bahn. Even before the strike, a significant drop in cargo volumes had been registered because many customers had canceled shipments, Deutsche Presse-Agentur (dpa) reported.

Leaving passengers scrambling to rebook or cancel their plans, the fourth strike since November also sparked warnings of huge costs to the state and industry when the German economy was already ailing.

'Cost on economy'

Deutsche Bahn estimated each strike day to cost "a low two-digit million figure," but industry experts warned the impact on the economy would be far bigger.

Michael Groemling of Cologne's Institute for Economic Research said nationwide train stoppages can cost the economy up to 100 million euros a day but warned that the impact "may not rise linearly in a strike that lasts several days, but partially multiplies."

Given the disruptions with sea freight over the Houthi attacks, as well as issues on road transport, "rough estimates suggest that in extreme cases, this strike can cost up to a billion euros," he said.

Tanja Goenner, managing director of Germany's Federation of Industries BDI, pleaded with the union to "come to its senses," saying the walkout would hurt the economy.

"There is a threat of further severe restrictions including production losses, or slowdowns or even shutdowns in industry," she said.

In addition to pay raises, the union calls for working hours to be reduced from 38 to 35 per week without a pay cut, a demand Deutsche Bahn has so far refused.

On Wednesday, the train operator again rejected the union's proposals as a basis for further negotiations, calling them a "repetition of well-known maximum demands," dpa reported.

Last year, Deutsche Bahn also clashed with the EVG rail union, representing around 180,000 non-driver rail personnel, reaching an agreement in late August.

The latest walkout breaks the previous record of a May 2015 action, also called by GDL, that lasted around five days.