A total of 78 dockers at the Port of Grangemouth’s container terminal began the first of two weeks of strike action on Tuesday.
The industrial action at the harbour, Scotland’s largest container port, is due to continue until 29 March when an overtime ban will begin.
The dispute has nothing to do with the town’s Ineos oil refinery but fuel deliveries might be affected.
The dockers, members of the Unite union, have been picketing outside the main entrance to the docks since their action began.
They said a decision by Port of Grangemouth’s owners Forth Ports to open up another road into the docks had caused them to picket the entrance to the Ineos terminal in addition.
Sources close to the strikers said petrol tanker drivers had indicated they would not cross the picket line.
The dockers are unhappy at the introduction of a new shift pattern which they say will force them to work every other weekend – something they say is currently voluntary – and will also amount to a “de facto pay cut”.
As lorries and tankers began to queue up, Unite regional officer Tony Trench said the move was the result of the “attitude of the employer”.
He said: “They don’t want to sit down and discuss anything.”
He added: “We have now released vehicles to go in but nothing is coming out. This could lead to a shortage of fuel.”
A spokesman for Police Scotland said: “Police are currently dealing traffic congestion around Gate One of Grangemouth Port on Powdrake Road in connection with the ongoing industrial action. Drivers in the area are advised to leave extra time for their journeys and to find alternative routes where possible.”
A spokesperson for the Port of Grangemouth said: “Unite’s decision to call a two week strike cannot be justified. We have been discussing with the union proposed changes to shift patterns at the Port of Grangemouth since May 2015. During that time their implementation has been delayed twice to allow Unite to put forward a workable alternative, which they have failed to do.
“Vessels now call at the port seven days a week and increasingly at weekends. Like any modern business, we need the flexibility to respond to our customers’ needs. Our staff and their union accepted the potential need for flexible shift patterns when this element of their employment contracts was agreed in 2011.
“We call on Unite to end this strike, get our people back to work, honour the contracts agreed in 2011 and reopen discussions on these necessary proposals.
“Meanwhile, with the exception of container quayside operations, the remainder of the Port of Grangemouth remains open for business and continues to operate.”