German rail travelers are facing massive disruption from a 20-hour strike by train drivers that began late Wednesday and is due to continue until 6 p.m. local time on Thursday.

Deutsche Bahn AG warned that millions of passengers will be affected and urged people to avoid unnecessary journeys or postpone travel plans.

“A strike timetable will be provided, but this only ensures a very limited basic service,” the company said in a post on X.

The GDL train drivers union has rejected Deutsche Bahn’s offer of 11% more pay and an inflation bonus of as much as €2,850 ($3,089). Its demands include a €555 increase in monthly pay and a four-day, 35-hour working week with full compensation.

Deutsche Bahn has said the union’s requests would increase its personnel costs by 50%.

GDL Chairman Claus Weselsky said Wednesday that Deutsche Bahn doesn’t appear to be interested in seeking a negotiated solution. GDL officials would nonetheless show up for talks planned for 11 a.m. in Berlin, the union said.

Under fire for frequent cancellations and delays, Germany’s rail operator has embarked on a modernization of the nation’s busiest routes by 2030 with more than €80 billion in government funding.

In March, its workers joined a strike along with peers in France and the UK to demand higher pay, causing severe disruption for travelers. Another strike was averted in May after the railway operator and the EVG union reached a settlement in a labor court.

A strike around the Christmas holiday period cannot be ruled out, Weselsky told the Berliner Morgenpost newspaper in an interview this month.