BERLIN - German engineering union IG Metall said on Monday 5,200 workers at 10 plants in eastern Germany had staged brief warning strikes to push for a shorter working week, with more strikes due on Tuesday.
The one-hour walkout at eastern plants of carmaker Volkswagen AG and Opel and a number of suppliers were aimed at reducing the working week to the western German level of 35 hours from 38.
"If we don't make progress with demonstrations, workers' protests and negotiations, we're going to have to resort to the ultimate weapon, and that means a full strike," regional IG Metall chief Hasso Duevel said.
Employers have said shortening the working week would remove eastern Germany's last remaining competitive advantage, kill off job creation and add a cost burden that many businesses in the region cannot shoulder.
Monday's strikes targeted plants in the eastern state of Saxony, including Opel's plant at Eisenach and VW factories in Chemnitz, Mosel and Dresden.
Further strikes are planned on Tuesday in Saxony and Brandenburg around Berlin.