German train drivers extended their unprecedented nationwide strike Thursday to passenger services, causing travel chaos for millions and drawing fierce criticism.
The work stoppage by the GDL trade union hit long-distance and regional rail services as well as commuter S-Bahn train networks from 0100 GMT.
The strike -- the union's sixth bout of industrial action since September -- kicked off with freight services on Wednesday, added passenger trains on Thursday and is due to continue until early Monday.
But German rail operator Deutsche Bahn announced it had taken legal action in a bid to halt the walkout, saying it wanted to "do everything it could" to resume service.
It said the strike had caused "massive disturbance" but that it aimed to ensure a third of intercity transport services kept running.
About one in three regional trains and S-Bahn services were running in the west and north of the country, about 40 percent in the south and between 15 and 30 percent in the east, the company said.
Politicians and industry groups have voiced fears about the impact of the strike, which is the longest in Deutsche Bahn's 20-year history, and will hit weekend celebrations for the 25th anniversary of the fall of the Berlin Wall.
Chancellor Angela Merkel insisted that the right to strike had to be carried out "responsibly" and "with a sense of proportion" in comments to reporters on Wednesday.
But she appealed for arbitration so the strikes would "for us as a country do the least possible damage".
Late Wednesday, the GDL union rejected an arbitration offer by Deutsche Bahn, which has slammed the latest walkout as "pure bullying".
GDL says Deutsche Bahn is stonewalling in talks over workers' demands for a five-percent wage hike and a shorter working week of 37 hours.
Union leaders also want to represent other groups of employees within Deutsche Bahn such as conductors, catering staff, dispatchers, and not just drivers.
- 'Irresponsible' -
Rail users at Berlin's main train station tried to stay patient despite the disruption during Thursday's morning rush hour.
Student Gloria Menner said she understood the strikers' anger but that it was "very annoying" to face a two-hour journey to get to university in the neighbouring city of Potsdam.
"I also work in the public sector and you can't go out onto the street all the time like that," another traveller, Anna Serafinska, said.
Deutsche Bahn said in a statement that it was aware its temporary injunction with the Frankfurt labour tribunal could fail as judges in the past had mostly ruled against employers.
"We accept this risk however and have extensively demonstrated to the court what numerous substantial offers we have put to GDL in the past," the company's head of personnel, Ulrich Weber, said.
The BDI Federation of German Industries criticised the union's action as "irresponsible" and warned of "enormous economic costs".
"Such a long strike will also lead to empty warehouses and therefore to incalculable risks of production shortfalls," it said in a statement.
With as many as two million visitors expected to travel to the German capital this weekend for events marking a quarter-century since the Berlin Wall was torn down, media commentators were also scathing.
"The train drivers are damaging themselves, the right to strike and democracy by abusing a celebratory day of freedom for their strike," Die Welt daily said.