The owners of a petrochemical plant have launched a legal action against the Unite union over alleged false allegations, reports the BBC.
The plant operator, Ineos, believes that the Unite union made false allegations during a dispute over the treatment of one of the plant's employees.
Stephen Deans has worked at the plant in Grangemouth, Scotland, for 24 years. He is also the chairman of the Falkirk Constituency Labour Party.
In July it emerged that the selection process for a new MP for the Falkirk constituency may have been rigged, prompting an investigation by the Labour Party, who temporarily suspended Mr Deans.
The investigation absolved Mr Deans of any involvement and he was reinstated in his role as local party chairman. However, the incident prompted Mr Deans' employer to launch its own investigation into whether his role as an employee was compromised by his political activities.
Workers' union Unite has now balloted 1,000 of their members based at the site over Ineos' treatment of Mr Deans, which they publically criticised in a statement on their website.
"It is now a matter of fact that Stevie Deans did nothing wrong within Falkirk CLP as it worked to select a Labour party candidate," read the statement.
"This [investigation] is nothing other than a sinister campaign to victimise and hound Stevie Deans out of his job," the statement continued.
The comment prompted Ineos to immediately warn Unite to remove the statement from their website or face a libel action for a false and defamatory publication.
Calum MacLean is the chairman of Ineos Petrochemicals UK.
"We will not be intimidated by union pressure. We cannot have one rule for union officials and another for everyone else on the site," he told the BBC.
On Friday last week workers overwhelmingly voted to support strike action to support Mr Deans.