Operations staff at the Port of Grangemouth are currently balloting for strike action over changes to conditions by employer Forth Ports.
Unite the union confirmed the ballot was ongoing this week over a dispute concerning changes to pensions and shift patterns.
A spokesman from Forth Ports said: “At Forth Ports we are committed to communicating effectively with the people who work in all our ports about issues that are important for them and to the company.
“We are currently discussing proposed changes to working patterns which are designed to better meet the needs of our customers. While these discussions are under way it would not be appropriate for us comment any further.”