FRANKFURT (Reuters) - Industrial workers in Germany started 24-hour strikes overnight, affecting companies including automotive supplier ZF Friedrichshafen [ZFF.UL] and lighting company Zumtobel <ZUMV.VI>, amid a dispute over wages and working hours.
Powerful German union IG Metall has called for full-day walkouts through Friday, firing a last warning shot before it ballots for extended industrial action that could be crippling to companies reliant on a well-oiled supply chain of car parts and other components.
Emboldened by the fastest economic growth in six years and record low unemployment, the union is demanding an 8 percent pay rise over 27 months for 3.9 million metals and engineering workers across Europe's largest economy.
The union has also asked for workers to be given the right to reduce their weekly hours to 28 from 35 to care for children, elderly or sick relatives, and return to full time after two years.
This is IG Metall's first major push for shorter hours since workers staged seven weeks of strikes in 1984 to help secure a cut of the working week to 35 hours from 40 hours.
Employers have offered a 6.8 percent increase but rejected the demand for shorter hours unless they can also increase workers' hours when necessary.
Across Germany, around 260 companies are expected to be hit by walkouts lasting 24 hours each this week in support of IG Metall's demands.
Workers at printing press maker Heidelberger Druckmaschinen in Heidelberg are among those downing their tools on Wednesday, as are staff at Kion's <KGX.DE> Still brand of forklift trucks in Hamburg and at valve maker Gestra in Bremen.
Workers at automotive supplier Robert Bosch [ROBG.UL] in Stuttgart are due to go on strike later on Wednesday, to be followed by Mercedes-Benz maker Daimler <DAIGn.DE> and sportscar firm Porsche <VOWG_p.DE> on Friday.
Both the union and the employers have left the door open to resuming talks after the planned strikes end on Friday but each said they demanded more willingness to make concessions.
(Reporting by Maria Sheahan; editing by Mark Heinrich)