The Ministry of Defence has negotiated a new £1.4 billion contract for the Royal Navy’s new attack submarine, the sixth in a total fleet of seven.

The submarine, named Agamemnon, is part of the Astute Class submarines.

The submarines are being built by BAE Systems in Barrow-in-Furness, Cumbria.

Defence secretary Sir Michael Fallon said: “This latest investment means we are well on our way to completing our fleet of Astute submarines. These are the most advanced submarines ever operated by the Royal Navy and are already providing unprecedented levels of stealth and attack capability across the world.”

Construction of the 7,400 tonne, 97-meter long Agamemnon began in 2012, and is underway in the Devonshire Dock Hall at Barrow.

Rear admiral Paul Methven, director Submarines Acquisition for the Submarine Delivery Agency, said: “The signature of this contract secures another world-class nuclear submarine for the Royal Navy. These are the most technologically advanced submarines we have ever operated, offering much greater firepower, better communications and more advanced stealth technology than their predecessors.”

Will Blamey, managing director of BAE Systems Submarines, said: “Securing the contract for the sixth Astute class submarine is a significant milestone for BAE Systems and the result of many years of hard work by our highly skilled workforce.”