REUTERS - A group of French workers facing layoffs obtained extra money after threatening to blow up industrial equipment at their plant, labour union representatives said on Friday.

The staff at JLG, a company that makes platforms mounted on cranes for fixing equipment high off the ground, were the third in France to make similar threats this month after workers from telecoms manufacturer Nortel and car parts maker New Fabris.

JLG workers at three plants in southwestern France had been on strike for three weeks over a management plan to lay off 53 of them. After hearing news of the threats made at Nortel and New Fabris, they decided to follow suit.

On Wednesday, they placed four of the cranes, with a total value estimated at 250,000 euros ($352,400), in a car park and surrounded them with gas cylinders and kindling.

After lengthy talks that lasted well into Thursday night, management met their demand that laid off workers receive 30,000 euros in compensation, and the strikers removed the gas cylinders and put the cranes back inside the factory.

"It's a shame that we reached this point. If management had wanted, we could have avoided this tough conflict," Christian Amadio, a JLG worker representative, told Reuters.

The Nortel workers obtained a resumption of negotiations with their management, while at New Fabris they obtained nothing and are still threatening to blow up their factory.

Such threats mark a new escalation in tactics used by disgruntled French workers after a spate of "bossnappings" earlier in the year in which managers were detained on company premises.

Authorities have used tough language to denounce such actions but have refrained from sending in the police to break up protests. The government wants to avoid an escalation of violence in a country with a history of labour unrest.