GRENOBLE (AFP)--Angry French workers holding four managers at a plant run by U.S. firm Caterpillar Inc. (CAT) demanded European intervention Wednesday to save hundreds of jobs.

Employees barricaded their bosses in an office Tuesday, in France's latest case of what has been dubbed 'boss-napping,' to demand new negotiations on 733 layoffs at the factory in the southern city of Grenoble.

On Wednesday morning, with police gathered outside, unions issued a call to President Nicolas Sarkozy and the European parliament, demanding funding be found to protect the workforce.

They said the money could come from the European Globalization Adjustment Fund, which Nicolas Benoit, the representative of the CGT union at the plant, said holds EUR500 million for such emergencies.

"If there's money to save banks and finance you should find some to save businesses," he declared, reflecting anger in France over Sarkozy's economic recovery plan.

Caterpillar factory director Nicolas Polutnik was being held along with the head of personnel and two other managers while some 50 employees mounted guard outside the building. Human resources director Maurice Petit, who suffers from heart problems, was allowed to leave in the early evening.

Early Wednesday the managers were given the traditional French breakfast of coffee and croissants by their captors.

It was the third time in March that executives had been held by French workers outraged at job losses sparked by the global economic crisis. A manager of a factory run by U.S. pharmaceutical giant 3M was held for more than 24 hours last week and the boss of Sony France was detained overnight March 12 by workers seeking better redundancy packages.

In those instances, police didn't intervene to free the managers who were released unharmed and no charges have been laid against the workers.

"We are holding them in the director's office," union official Benoit Nicolas told AFP Tuesday. "They are a little stunned."

During mid-afternoon, union officials escorted journalists into the offices where the managers were being held while police officers took up positions at the entrance of the plant.

Polutnik defended the layoff plan as the only way to save the company and said he was unable to reopen negotiations while being held captive.

"We do not have the freedom of movement that would allow us to give negotiations a chance," he said as employees listening nearby booed.

Union representatives told AFP Wednesday negotiations were scheduled for 0900 (0700 GMT) if the captured bosses agreed. Workers were demanding a minimum EUR30,000 in severance pay, much more than the EUR10,000 Caterpillar was offering as minimum compensation.

Union representative Alexis Mazza said the five, then including Petit, were told they will "stay here and sleep here" after talks hit an impasse.

"They don't want to renegotiate, they say they are up against the wall, that they have no money and that the company is in jeopardy," said Mazza.

Caterpillar workers were on strike for a second day Tuesday at two plants that produce construction equipment engines in the Grenoble region.

Management announced plans to cut 733 jobs out of 2,800 at the two plants Feb. 17.

France has also seen strikes and protests over big bonuses paid to managers, as the crisis has sent the number of French jobless shooting up monthly to reach 2.4 million. The government hasn't spoken out strongly against 'boss-napping,' but Families Minister Nadine Morano has said such radical tactics weren't the answer to job losses.