Opel labor leader Klaus Franz called on General Motors to pick a buyer for its European unit this week, and threatened spectacular measures if the U.S. group did not make a decision.
On Friday GM failed to reach a decision either in favor of the Canadian automotive firm Magna , which is Germany's preferred buyer for Opel, or rival bidder RHJ International , leaving the carmaker's fate up in the air.
We have run out of patience, Opel's works council head Franz told Deutschlandfunk radio on Monday.
We have been calm so far, listened diligently and made comments, but that is over now. If nothing changes from General Motors' side by the end of this week, then we will be active, and there will definitely be spectacular measures from us, he said. German Chancellor Angela Merkel also expressed her regret on Sunday at GM's failure to choose a buyer and said a decision was urgently needed for the carmaker's future.
GM, which emerged from bankruptcy protection on July 10, last week agreed to sell its Saab car business to Koenigsegg, a tiny Swedish luxury carmaker, the first in a series of big disposals the U.S. group is planning as it slims down.
Delays have also dogged negotiations to sell GM brand Hummer. Chinese reports said over the weekend that regulators there had approved Tengzhong's bid for Hummer, but the Chinese company said it was still awaiting official word.
In Europe, talks to sell Opel have been dragging on for months, and the German government and GM now seem to be split over who should be allowed to buy the company.
Berlin, which is facing a federal election on September 27, has offered financial backing for Magna's bid because it believes it would be the best option to save jobs at Opel.
In Germany, Opel employs over 25,000 people in four major plants making models including the three-door Corsa subcompacts and Zafira vans. In the U.K., there are two factories that produce automobiles under the Vauxhall badge. Opel has other facilities in Belgium, Poland and Spain.
Opel and sister brand Vauxhall sold just over 560,000 cars in Europe in the first half of the year for a market share of 7.6 percent, according to data compiled by the ACEA auto industry association.
A Magna victory would be a coup for its founder and chairman, Frank Stronach, who left Europe a poor toolmaker half a century ago and built his company into one of the world's biggest automotive suppliers.
It would mark a setback for Leonhard Fischer, the former investment banker and turnaround specialist who runs RHJ.
The failure to make a decision on the firm's future drew angry reactions from a number of German politicians at the weekend, while they reaffirmed their support for Magna's bid.
Berlin and GM are expected to resume talks this week.
(Writing by Paul Carrel and Maria Sheahan; Editing by Will Waterman)