The US firm Molex has shut a car parts factory in southern France on grounds of “security” after angry workers allegedly assaulted a manager.
The company accused striking workers of assaulting and injuring the manager, Eric Doesburg. A union official told the BBC that “a few eggs were thrown”.
“He did not receive any blows,” Camille Ramon of the CGT union said.
Workers at the Villemur-sur-Tarn plant are protesting over plans to relocate production to the US in October.
“They are preventing anyone getting onto the site,” Mr Ramon said on Thursday.
About 160 demonstrators have gathered at the plant, where the dispute has paralysed production of electronic components since 7 July.
Molex is in talks with union representatives about the relocation plan, which could see 283 workers lose their jobs.
The unions argue that the plant is economically viable and that the current offer of compensation for layoffs is unacceptable.
There have been several incidents of workers threatening violence against employers elsewhere in France this year, amid a spate of factory closures and redundancies.
In some cases French workers have taken managers hostage in “boss-nappings”.
A statement on the Molex website said the plant was closed “to help ensure the safety of employees and security of the facility after an employee and two security guards were injured” on Tuesday.
“They were physically attacked and injured by a group of approximately 40 people who included members of the local Works Council and union representatives,” it said.
“The employee who was attacked is based in the US and was in France to assist in the negotiations with the Works Council on a social plan related to the proposed closure of the plant. Two French security guards were also attacked and injured and property was damaged.”
Molex quoted Mr Doesburg as saying police failed to respond to repeated calls for assistance.