The owners of Rosyth Dockyard have said Scottish independence could put up to 800 jobs at risk.
They believe it’s unlikely further Navy contracts would come to the Forth if Scotland opts to break away from the UK.
Babcock managers have told Rosyth workers that a “Yes” vote could mean the end of further work.
But they have admitted that even a “No” vote would not necessarily safeguard Rosyth’s future.
A Scottish Government spokesman said UK defence contracts could still be carried out in an independent Scotland.
Yesterday, Babcock officials briefed the joint trades unions at Rosyth on their view of what could happen if the Scottish public vote for independence.