Police are still hunting for the whistleblower who warned that Britain's Trident nuclear missiles are vulnerable to a terorrist attack and a "disaster waiting to happen".

William McNeilly went missing after publishing an 18-page dossier warning of security and safety lapses on board nuclear submarines.

The Royal Navy confirmed Mr McNeilly is a member of the naval service and said it is “concerned for his whereabouts and wellbeing”.

Mr McNeilly, 25, made the comments in an online post including his Navy ID card. He claims he raised concerns with senior officers but decided to publish his claims as his concerns were ignored.

The Navy said many of the claims are “subjective and unsubstantiated personal views, made by a very junior sailor, with which the naval service completely disagrees”.

A Royal Navy spokeswoman said: “The Royal Navy takes security and nuclear safety extremely seriously and we are fully investigating both the issue of the unauthorised release of this document and its contents.

“The naval service operates its submarine fleet under the most stringent safety regime and submarines do not go to sea unless they are completely safe to do so.”

Peter Burt of the Nuclear Information Service, said: “William McNeilly is a brave young man who has done not only his colleagues in the submarine service but the whole nation a service by exposing the risks that submariners face because of cost-cutting, staff shortages and lax management.

“The Ministry of Defence’s nuclear programme operates to far lower safety standards than the civil nuclear sector because independent regulators are not allowed to scrutinise its activities, and because much is covered up under the pretence of security.