Updated 4.14pm

A MAN HAS been arrested after a shooting on board a nuclear submarine in the British port of Southampton that has left one person dead and another in a life threatening condition.

Sky News reports that an active serviceman is being held by police with reports that he used a 9mm pistol.

Police were called to Southampton docks where the HMS Astute had been berthed since Wednesday, at 12.12pm following the incident.

A spokesperson for Hampshire police said there is no risk to public safety and the incident is not linked to terrorism.

Southampton’s mayor and city council leader were on board the submarine at the time, according to the BBC.

The 97m long HMS Astute is usually based at the Faslane Naval Base in Clyde in Scotland.

The Royal Navy website describes the vessel as “the largest and most powerful nuclear attack submarines ever built for the Royal Navy.”

It was in the news in October last year when it ran aground on a shingle bank between the Scottish mainland and the Isle of Skye and remained trapped there for several hours.

BBC reports that the submarine weighs 7,800 tonnes which is equivalent to nearly 1,000 double-decker buses.

Its armoury includes spearfish torpedoes and Tomahawk cruise missiles which are capable of delivering pinpoint strikes from 2,000 kilometres away.

Its own nuclear reactor means it does not need refuelling and it makes its own air and water allowing it to navigate the globe without a need to surface.