A union representing many of Germany's train drivers has called for another strike in a long and bitter dispute with the state-owned main railway operator over working hours and pay, drawing sharp criticism from the country's transport minister.

The GDL union called on drivers of Deutsche Bahn's passenger trains to walk out for 24 hours starting at 2 a.m (0100 GMT). Tuesday. Meanwhile, drivers of freight trains will walk off the job from 6 p.m. (1700 GMT) Monday.

ONGOING STRIKES THWART FLIGHTS, TRAIN RIDES OUT OF GERMANY

The walkout was announced on Sunday evening, in keeping with a union announcement last week that it would no longer give a 48-hour notice before striking. It follows a 1 1/2-day walkout last week.

The German national flag is seen on a sunny day surrounded by some clouds at the Chancellery in Berlin, Germany, April 29, 2016. REUTERS/Fabrizio Bensch - RTX2C625

The German national flag is seen on a sunny day surrounded by some clouds at the Chancellery in Berlin, Germany, April 29, 2016. (REUTERS/Fabrizio Bensch)

The main sticking point in the dispute that has dragged on for months is GDL's demand for working hours to be reduced from 38 to 35 hours per week without a pay cut.

In several weeks of talks between the two sides, moderators suggested a reduction from 38 to 36 hours by 2028, but details of their proposal didn't satisfy GDL. The union demanded a new offer by Sunday evening, which wasn't forthcoming.

Transport Minister Volker Wissing told the Bild newspaper that "striking instead of negotiating is irresponsible." He pressed GDL to resume talks and said formal arbitration proceedings must be launched.

GDL chairman Claus Weselsky "is overstepping the mark further and further," Wissing added.

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Private operators run some regional train services in Germany, unaffected by the dispute with Deutsche Bahn.