The strike is to run from 02:00 am local time (01:00 am GMT) on Wednesday until 06:00 pm (05:00 pm GMT) 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 06:00 pm.

"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 on 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.

(Reporting by Katharina Loesche, Writing by Linda Pasquini; Editing by Bernadette Baum and Louise Heavens)