GRENOBLE, France (AP) -- Angry French workers have for years resorted to "boss-napping" as a negotiating tactic when times get tough, but rarely faced any punishment. Four Caterpillar executives recently held hostage hope to change that.
The four have sued in criminal court after being locked in the Caterpillar factory in Grenoble last month for more than 24 hours, a union official said Friday. The lawsuit did not name any specific suspects, leaving it up to investigators to determine who was responsible.
French workers have seized managers at several companies in recent weeks as the economic downturn forced more and more businesses to lay off or cut back -- including executives at Sony, Post-It maker 3M and the plant run by U.S. manufacturer Caterpillar.
The practice, while rare, has persisted in France for years. Managers are not physically harmed, are usually released after a few hours and don't press charges.
But the Caterpillar lawsuit is the latest sign of a hardening in tensions between French workers fearing job losses and companies struggling with recession. After weeks of peaceful strikes and protests, workers at an auto parts factory north of Paris ransacked offices Tuesday after a court refused to block the factory's closure.
Caterpillar plans to layoff about 600 or 700 of the 2,700 employees at its two factories in southeast France -- among thousands of job losses worldwide at plants run by the Peoria, Illinois-based Caterpillar Inc. amid slumping demand.
French workers demanding a better layoff package seized the four managers March 31. They were released the next day.
Union official Pierre Piccarreta said the Caterpillar bosses had sued in criminal court for "sequestration," or holding victims against their will. A police official investigating the hostage-taking confirmed the lawsuit but spoke on condition of anonymity because the official was not authorized to discuss the probe.
Caterpillar officials could not immediately be reached for comment.
"It's a declaration of war," said Pierre Janot, a lawyer for the Caterpillar workers council, saying the lawsuit could complicate efforts to reach an accord over the layoff conditions.