Five Amazon sites in Germany were hit by fresh walkouts on Monday in a long-running pay dispute with the US online retail giant.
Services sector union Verdi said around 2,000 employees had taken part in the stoppages at the five Amazon centres in Leipzig, Bad Hersfeld, Graben, Rheinberg and Werne.
Verdi wants Amazon to bring the pay of its 9,000 workers in Germany in line with wages in the mail order and retail industry.
But Amazon argues that its distribution centres are logistic sites and that it pays its staff accordingly.
Stefanie Nutzenberger, a Verdi board member, said the participation in the strikes sent a "clear message" that Amazon workers would not cease in the "fight for sustainable and good work conditions".
The stoppage will continue through Tuesday at the Werne site, and through Wednesday at the other four centres, the union said.
Amazon has a total of nine sites in Germany and has been hit by several walkouts over the past 18 months.