The Fiji Sugar and General Workers' Union says its members at the Lautoka sugar mill are being intimidated by the mill management.
The union is considering strike action over what it says is a huge fall in the real value of wages during the past 7 years.
It says over the weekend workers at the mill were required to complete a form saying whether they would strike.
The union also says the Lautoka mill has been offering five year contracts to retired mill workers and is stopping on site union meetings.
It calls this irresponsible and showing absolute contempt for workers' rights.
It says the workers have taken a secret ballot for strike action as required by law and the results have been validated by the Ministry of labour.
The union says it will determine what action to take later this week.
The union also claims the Fiji Sugar Corporation has plans to bring in workers from India if the strike goes ahead.