Strike action begins at Faslane and Coulport naval bases
Civilian staff at the Faslane and Coulport naval bases have begun a series of strikes in a dispute with Babcock Marine over workers' rights.
Unite members are taking part in a continuous overtime and on-call ban.
It coincides with a series of staggered periods of strike action, which the union said would have an impact on naval operations until 15 June.
Babcock Marine said it was "disappointed and perplexed by Unite's actions".
Unite said the strikes would affect all areas at the bases, including the nuclear operations department.
The Faslane base on the Clyde is home to the UK's fleet of Trident nuclear submarines.
Unite has accused Babcock of a "systematic campaign to undermine workers", claiming it had withdrawn facilities for shop steward meetings and was "failing to meaningfully consult and negotiate with the trade union".
The union represents a range of workers at the two bases, including cleaners, housekeepers, logistics operatives, drivers and mail staff.
It also has members in radiation monitoring and strategic weapons support roles.
Unite regional officer Stephen Deans accused Babcock of trying to "bypass" the union and undermine workers' rights.
He told the BBC's Good Morning Scotland programme: "The agreed consultation and negotiation structures that we have at the base have been ignored by Babcock.
"Our elected representatives have been ignored mostly, or presented with decisions rather than being consulted before decisions are finally made.
"Our representatives have been victimised and harassed by management."
'Profit before service'
Mr Deans added: "Our members have been forced into this action today. Management at Babcock Marine have engineered a complete breakdown of normal relations with workers.
"Our fear is that they want to try and undermine workers' rights so they can cut jobs and service quality through more outsourcing.
"They want to squeeze as much money as they can out of being involved in the nation's defence. But our members work hard supporting the Royal Navy's operations and will not allow profit to be put before service."
Babcock Marine said it had offered "reasonable solutions" to all of the issues raised by Unite.
A spokesman added: "We absolutely refute the allegations that we are attempting to undermine our relationship with the trade union and wider workforce or that we are engaged in a wide-ranging plan to outsource services.
"Our workforce at HMNB Clyde do a magnificent job in support of the Ministry of Defence and the Royal Navy and it is disappointing that most will get no direct benefit from the issues raised with us.
"We are working closely with our customer and the 1,100 Babcock employees who are not involved in this industrial action to minimise any impact to the smooth running of HMNB Clyde.
"We remain committed to finding a positive resolution to this dispute and hope to have further discussions with Unite facilitated by ACAS in the next few days."