* Union seeking 8 percent pay rise for 3.9 million workers
* Employers offering 6.8 percent increase
* Union emboldened by fast economic growth, low unemployment
FRANKFURT, Jan 30 (Reuters) - Workers at German companies including carmakers Daimler and Porsche and automotive supplier Bosch are set to stage strikes over the coming days amid a row over wages and working hours, union IG Metall said.
Walkouts lasting 24 hours at a time will begin late on Tuesday and run until Friday, the union has said, after its members voted overwhelmingly in favour of action after last-ditch regional talks over wages and working hours failed to reach a deal at the weekend.
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 Germany.
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.
Employers have offered a 6.8 percent increase but have rejected the demand for shorter hours unless they can also increase workers' hours when necessary.
Nearly a million workers have already taken part in short walkouts lasting no more than a few hours at a time across the country this month to support IG Metall's demands.
An escalation to 24-hour strikes is the union's 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.
Across Germany, around 260 companies are expected to be affected by walkouts this week.
Workers at automotive supplier ZF Friedrichshafen in the southwestern state of Baden-Wuerttemberg will go on strike from 5 am local time (0400 GMT) on Wednesday, while staff at Mercedes-Benz maker Daimler and sportscar firm Porsche will walk out on Friday, IG Metall said.
"The employers haven't sufficiently budged in negotiations, now we are going to push them into action with full-day warning strikes," said Roman Zitzelsberger, head of IG Metall in Baden-Wuerttemberg, where 16 hours of negotiations failed to yield a deal.
To the north, workers at Kion's Still brand of forklift trucks in Hamburg and at valve maker Gestra in Bremen will down their tools.
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 Gareth Jones)