ELLEGARDE-SUR-VALSERINE, FRANCE - French workers on Wednesday held three British executives and a local manager at a British-owned adhesives factory after talks on the plant's closure hit a wall.

In the latest of a string of so-called 'bossnappings", staff at the plant owned by British glue-maker Scapa barricaded their bosses in their offices late Tuesday and kept them there overnight, union leaders and the company said.

But the four managers at Bellegarde-sur-Valserine in southeast France were allowed to leave on Wednesday evening after talks organised by the town hall, an AFP journalist said.

'We were able to come to a compromise on the layoff packages,' said Jean-Jacques Van Slambrouck from the company's workers' council.

Workers said the management had agreed to nearly double the total severance package to 1.7 million euros (2.25 million dollars). They are expected to decide on the new offer on Thursday.

The sequestration came a day after President Nicolas Sarkozy vowed to put an end to the practice, saying workers angry over layoffs must nevertheless obey the law.

'We came to the end of the road in terms of negotiations on the layoffs and the workers, who became desperate, decided to detain these managers,' said union official Fabrice Clappe.

Workers detained the executives after a breakdown in negotiations over the settlement deal for some 60 laid-off staff.

Three British executives were held captive - the director of Scapa's European operations, the personnel manager and the finance director of Scapa France - along with Scapa France's general manager, a French national.

'It was a great disappointment,' European finance director Ian Bushell said, speaking from Scapa's headquarters in the northwestern English city of Manchester.

'We are aware that in France there was recently a number of circumstances in which unions have held hostages but it was not envisaged in our case, a number of meetings took place before,' he added.

Union leader Christophe Bougret said the managers 'can negotiate up there, in England. We've decided to trust them.'

While talks took place at the town hall, workers laid a red coffin in front of the factory and waved banners that read ironically 'Thanks for our future'.

Scapa announced in February it would close its plant in Bellegarde after the market for car industry adhesives collapsed by 50 percent in 2008.

Workers at a Caterpillar plant last week released four managers who were held for 24 hours until the US-owned company agreed to reopen talks on compensation for hundreds of laid-off staff.

In March, a manager was held at a factory run by US conglomerate 3M and the boss of Sony France was detained overnight by workers outraged at job losses sparked by the global downturn.

None of the workers have faced charges over the 'bossnappings' but Sarkozy suggested this week that authorities were ready to clamp down on the tactic.

'What is this business of sequestering people' We have the rule of law, and I will not let matters go on like that,' Sarkozy said.

'We can understand that people are angry, but this anger will subside with answers and results, not by aggravating matters with actions that are contrary to the law,' he added.

Recent polls show that up to half of French people believe workers are justified in taking executives captive to seek better redundancy packages during the economic crisis.