The UK government has been warned that possible cuts to the police force which guards Britain's nuclear arsenal could threaten national security.
The Defence Police Federation, which represents the Ministry of Defence Police (MDP), said the civilian forced faced cuts of up to 15% in its numbers.
It said this could erode safety standards at sites such as the Trident submarine base at Faslane on the Clyde.
The Ministry of Defence (MoD) said safety was of “utmost importance”.
With the UK government still attempting to balance its books, departments across the board have faced pressure to make savings.
Following the Strategic Defence and Security Review (SDSR) in 2010, the MDP lost about one third of its workforce.
Chairman of the Defence Police Federation (DPF), Eamon Keating, said the existing 2,600 MDP officers could be cut by another 15%, following the SDSR in November 2015.
In his speech to the DPF conference on Thursday, which is due to be attended by defence minister Lord Howe, Mr Keating will warn against further cuts and of using soldiers to plug any gaps created.
He will say: “There have been suggestions that the MDP's role in guarding the nuclear deterrent might change.
“This is the most important job we do and any change to our role in safeguarding Trident impacts on the very future of the MDP, and on public and national security.”
He will warn that the force is “highly skilled” and better placed to deal with civilian protesters than soldiers. Using military personnel would also mean that they could not be deployed elsewhere, the federation chief will say.
“It is because of the unique nature of our training and authority that we would have grave concerns if the role of the MDP in guarding the nuclear deterrent is reduced or replaced, especially by any group not subject to public scrutiny or accountability as we are,” Mr Keating is set to tell delegates.
'Limit of resources'
Mr Keating said the force could not provide the same level of security with fewer staff and that it had worked at the limits of its resources for more than five years.
A Ministry of Defence spokesman said: “The security at all of our nuclear facilities is of the utmost importance, and the MoD has several security providers which deliver this capability.
“Our arrangements are frequently tested and kept under continual review. We would never make changes that would place these in jeopardy.”