GRENOBLE (AFP)---Angry French workers holding their managers hostage at a bulldozer plant run by U.S. firm Caterpillar Inc. (CAT) won a promise Wednesday from President Nicolas Sarkozy that he would meet their leaders.

Employees at Caterpillar's factory in the southeastern city of Grenoble barricaded bosses inside an office Tuesday after talks on a compensation deal for 733 workers facing redundancy broke down.

Human resources director Maurice Petit, who suffers from heart problems, was allowed to leave, but factory director Nicolas Polutnik was still being held Wednesday along with the head of personnel and two other managers.

"Caterpillar is a firm that makes earth-moving equipment and which works mainly in the U.S. The collapse in demand has been 80%," the French leader said, in an interview with Europe 1.

"I will save the site. I will meet the union leaders since, if I understand right, they called for my help and I understand this. I won't let them down."

It was not immediately clear what Sarkozy's promise amounted to: the "site" as such isn't under threat, but 733 of the firm's 2,800 jobs at two plants in Grenoble are due to be cut.

Nevertheless, Sarkozy's failure to criticize the workers for denying the bosses their freedom of movement could give encouragement to the organizers of increasingly militant protests across the country.

Earlier Wednesday, union leaders at the plant had issued a call to both Sarkozy and the European parliament, demanding funding be found to fund more generous redundancy packages.

Union representatives told AFP Wednesday that negotiations were scheduled for 0900 (0700 GMT) if the captured bosses agreed.