Britain's ability to defend itself has been called into question after an investigation found Navy warships are so loud they can be heard 160km away by Russian submarines.

Rear Admiral Chris Parry, a former director of operational capability for the Ministry of Defence, said the 1 billion ($1.7b) Type 45 destroyers are "as noisy as hell" and sound like "a box of spanners" underwater.

It comes amid warnings that years of defence cuts and expensive procurement contracts with a small number of large defence firms has left the military with an "existential minimum" amount of equipment.

The Ministry of Defence spent 3.5b on each of the Army's Ajax tanks, but they are unable to fit on board transport aircraft without needing to be dismantled, according to a report by the Sunday Times.


A further 1.2b was spent on 54 Watchkeeper reconnaissance drones, which have not entered frontline service for 12 years.

Long-rumoured problems with the Navy's fleet of six Type 45 destroyers that left them totally powerless were confirmed early this year. The Ministry of Defence admitted that "reliability issues" had affected the ships and said it was considering upgrades.

The warships were designed to work in the cool waters of the North Atlantic, but in hotter climates, the jet engines experienced problems with heat, causing them to shut down.

Parry said: "We used to put little wooden wedges between the hatch clips and the hatches in my destroyer to stop them rattling so we could keep the noise down ... Noise suppression has been probably the biggest dirty secret since the end of the Cold War that people have been cheerfully ignoring."