U.S. and international unions have accused Ray-Ban maker Luxottica, the Italian arm of eyewear giant EssilorLuxottica (ESLX.PA), of violating workers’ right to unionise at a U.S. plant in Georgia and asked the Italian, French and U.S. governments to mediate.

In a statement sent to Reuters, the Communications Workers of America (CWA), together with the AFL-CIO and two other workers’ groups, alleged that managers of the Luxottica plant in McDonough, near Atlanta, Georgia, unleashed an “aggressive and fear-inducing” campaign to discourage its 2,000 employees from seeking union membership.

The unions filed a complaint on Thursday under guidelines for multinational firms set by the Organisation for Economic Cooperation and Development (OECD), which say multinational firms should not interfere with workers’ organising rights.