Workers facing the sack from an air cargo company released the two managers they held overnight at Paris's Roissy airport yesterday after a court official intervened, trade union representatives said.

Around 60 workers had prevented Servisair Cargo directors Abderrahmane El-Aouffir and Andy Cowie from leaving the firm's offices after they had refused to meet their demands for better layoff terms.

But workers released both men after a bailiff intervened on their behalf. Union representatives then headed to local law courts to try to negotiate improved redundancy terms with a court-appointed administrator and a government official.

The detention of the two managers was the latest case of so-called "boss-napping" to hit recession-bound France this year, prompting the government to urge restraint.

Servisair, a division of French industrial services group Derichebourg, which has 337 employees, went into administration in March.

The workers want €30,000 pay-offs, but unionists said Mr El-Aouffir had offered them just €1,400 or transfers to new positions within the group as refuse collectors.

Mr El-Aouffir told French television the situation had been tense.

"I understand (the anger) but I don't think this is the solution for finding a way out of the conflict," he said.

Earlier this year staff at French plants run by Sony, 3M and Caterpillar protested job losses by holding managers overnight at their workplaces. More recently, workers have also threatened to blow up factories to demand better redundancy payments.

French Labour Minister Xavier Darcos criticised the continuing militancy.

"Threats and ultimatums are not the answer to anything," he told French state television.