HELENSBURGH'S MP says reports that the UK's entire fleet of attack submarines is not on active operations are “astonishing”.

Brendan O'Hara, who is also the SNP's defence spokesperson, was responding to national news reports at the weekend that only one of the Trafalgar and Astute classes of nuclear submarine is currently at sea – and that vessel is conducting trials and not on active service.

Five of the seven submarines in the two classes are reportedly having refits or maintenance, while a sixth is understood to be undergoing repairs after crashing into a tanker.

One report claimed that defence chiefs had not informed Prime Minister Theresa May about the situation.

Mr O'Hara said: “Reports of all seven attack submarines being out of action are astonishing.

“First there was the recent Trident malfunction fiasco, now we have this chilling situation. How can we possibly trust those in charge of our defence when we hear about this utter incompetence and yet another Whitehall nuclear cover up? It is a scandal.

“This latest Whitehall farce could be dangerously undermining the very core of the UK government’s defence position of the continuous at-sea deterrent.

“With the costs of Trident ballooning out of control, the remainder of our conventional defences are being cut to the bone to pay for it. We must have a basic right to know if it is fulfilling its role.

‘’Do we presently have an operational continous at-sea deterrent? Has it been in interrupted – and if so for how long?

“Do we have any operational submarines currently at sea? Was the prime minister told of any of these problems or were officials so scared of the reaction that they concealed it from her?

“These are all questions I have submitted to the Ministry of Defence.

“What is also worrying is whether essential repairs and maintenance, now clearly desperate and urgent, will once again cut into the ever dwindling money-pot to pay for our most basic of conventional defences.”

The new Astute-class submarines cost nearly £4 billion to build and were delayed by more than four and a half years.

One member of the class, HMS Ambush, collided with a ship off Gibraltar last summer, damaging its outer hull, though its nuclear plant was not affected and no crew members were injured.

The oldest of the four remaining Trafalgar-class submarines has been in service for more than 30 years.

A Ministry of Defence spokesperson said: “The Royal Navy's attack submarines meet their operational tasking and will continue to do so over the next decade. 

“It is not uncommon to have temporary small fluctuations in overall numbers during transition from one class to another.”