The Union of German Train Drivers (GDL) on Monday said it has called on employees of state-owned Deutsche Bahn (DB) to go on a multi-day strike again, which would mark the fourth round of strikes as it further escalated a wage dispute after refusing a new tariff offer submitted by the rail operator on Friday.

The strike will run from 2 a.m. local time (1 a.m. GMT) on Wednesday until 6 p.m. on the following Monday, the union said in a statement in the early Monday hours. Cargo train drivers were called to begin their strike on Tuesday at 6 p.m.

Union members at DB Cargo, which is responsible for freight transport, had already been called to strike from 6 p.m. on Tuesday, Germany's Deutsche Presse-Agentur (dpa) reported.

"With the third and supposedly improved offer, Deutsche Bahn AG has once again shown that it is pursuing its previous course of refusal and confrontation undeterred – with no trace of any intention to reach an agreement," GDL boss Claus Weselsky said in a statement.

"Deutsche Bahn relies on compromises; the GDL exacerbates the conflict beyond measure," a spokesperson for Deutsche Bahn said Monday.

"Anyone who does not even come to the negotiating table with a new offer of up to 13% (wage increase) and the possibility of a 37-hour week with the same salary is acting absolutely irresponsibly."

Deutsche Bahn and the GDL have been fighting over a collective wage agreement since the beginning of November, with the union seeking a reduced working week for its shift workers, from 38 to 35 hours, on current wages.

Deutsche Bahn has offered flexibility on working hours but refused to reduce them without a pay cut.

The railway said that longer trains with more seats would be used "in order to get as many people as possible to their destination" and that passengers would be free to use tickets booked for the strike period at a later date instead.

The latest strike could quickly add up to a billion euros in damage, considering that other transport routes have also been disrupted by the situation in the Red Sea, Michael Groemling, from the IW Cologne Economic Institute, said.

"Something is brewing," said Groemling. The German economy is already in recession. "This is now threatening to worsen," he said.

Commerzbank chief economist Joerg Kraemer said the strike could cost the transport sector 30 million euros ($32.66 million) a day, but significantly more damage would be done if factories had to stop production due to supply problems.

In addition, the strike was adding to the already tarnished image of Germany as a business location, he said.

It also said an extremely limited emergency timetable of long-distance trains and local commuter S-Bahn rail service would continue through the strike but warned of major disruptions throughout the country.

The looming six-day strike at Deutsche Bahn is expected to be the longest so far, with the previous one lasting for five days in 2015.

German Chancellor Olaf Scholz expressed hope on Monday for a quick settlement to the wage dispute between Deutsche Bahn and the GDL union and maintained his call for an amicable agreement, as per a dpa report.

However, a spokesperson for Scholz stressed that the chancellor would not interfere in the labor fight and respected the autonomy of collective bargaining in Germany.

Before the turn of the year, the GDL paralyzed large parts of passenger transport in two strikes, followed by a three-day strike with a similar effect in January.