Staff at Devonport Dockyard are to vote on taking industrial action. More than 2,000 members will take part in the ballot by Amicus, GMB, the T&GW and UCATT unions.
The industrial action vote follows the rejection of a 3% pay offer by DML. Unions said they were campaigning for a vote in favour of industrial action.
Dockyard company DML said it was engaged in discussions with trade union representatives over the current round of pay negotiations.