The four Caterpillar executives who slept on a carpet overnight after being held by workers in the latest case of bossnapping in France were due to be released today after President Sarkozy pledged to save their factory.

In a radio interview, the French president said that he would meet union representatives from Caterpillar, the American heavy equipment manufacturer, in an attempt to end the stand-off.

Nicolas Polutnik, the director of the group's factory in Grenoble, south east France, has been held since yesterday morning along with three senior colleagues as workers demand bigger redundancy payments. A fifth executive was released after falling ill.

An employee said the four hostages were given croissants for breakfast ahead of a fresh round of talks later today over Caterpillar's plan to shed 733 jobs in France.

After unions called on Mr Sarkozy to push for European Union funds to prop up the US manufacturer's French division, he said: "I am going to save the plant. I will receive all the unions because they've called on me for help, as far as I can understand. We won't let them down."

Although Mr Sarkozy's promise was greeted with scepticism at the factory, unions said they would release the hostages after the group agreed to renegotiate the redundancy package.

"It's good that he's spoken out. Now he has to follow it up with action," said a spokesman for the left-wing Confédération Générale du Travail union.

Commentators pointed out that Mr Sarkozy had made a similar promise at an ArcelorMittal steel plant threatened with closure the day after his marriage to Carla Bruni last year. The plant closed this week.

With Caterpillar predicting a 55 per cent drop of orders between 2008 and 2009, the group is planning to shed up to 20,000 jobs worldwide.

But French unions point out that the company made a $3.5 billion (£2.4 billion) profit last year and are demanding a minimum lay-off payment of €30,000 (£27,500). Caterpillar has offered €10,000.

The two other bossnappings over the past month were also sparked by a dispute over redundancy terms.

At Sony France, the chief executive and director of human relations were held for a day by workers demanding better payments. Two weeks later, the French industrial director of 3M, the US conglomerate, was detained for two days.

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