Workers at the Faslane naval base will hold a mass meeting tomorrow to discuss potential strike dates in a row over pay.
Members of Unite at the Clyde nuclear site have voted for industrial action in protest at a 1% pay rise.
The union has accused employers Babcock of refusing to enter conciliation talks, warning that the lack of negotiations has increased the likelihood of the first large-scale strike in 42 years at Faslane, and another Clyde base at Coulpourt.
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Unite national officer Ian Waddell said: "Babcock knows this pay imposition is completely unacceptable to the workforce but its refusal to enter into conciliation
"Unite offered the most obvious route forward through Acas only for the company to swiftly refuse our olive branch.
"Alarm bells at the MoD must be ringing when we have pay disparity across nuclear submarine bases operated by the same private sector contractor, that can easily pay more, hiding behind the UK government's public pay cap to impose cuts on its Clydeside workers.
"Babcock has fuelled the sense of injustice among a loyal workforce that's simply not prepared to be the poor relation in a highly profitable company."