SILVER WORTH an estimated €173 million has been discovered on the wreckage of a WWII-era ship in international waters some 300 miles off the west coast of Ireland.

A US company called Odyssey Explorations discovered the treasure trove almost 5,000 metres below the Atlantic.

Odyssey says the Record of War Losses kept by insurance firm Lloyd’s suggest that around 7 million ounces of silver were on board when the ship sank 70 years ago. Worth £600,000 in 1941, the silver is estimated to be worth £150 million today (€172.6 million).

The SS Gairsoppa was travelling from Calcutta to London when it was torpedoed by a German U-boat on 17 February 1941.

The cargo steamship, in use by the British Ministry of War, had been trying to rejoin a convoy of British ships and was running low on fuel at the time of the attack. The ship had abandoned its plan of joining the convoy and was instead heading to Galway when it was sunk about 300 miles south-west of Galway Bay.

Of the 85 men on board, only one made it ashore alive after spending 13 days in a lifeboat.

Odyssey Exploration says it analysed records about the ship’s final voyage and details about the shipwreck to identify the site as that of the Gairsoppa. It also says it is “confident” that it can salvage the cargo in an efficient and timely manner.

Odyssey’s CEO Grey Stemm says the ship is sitting upright and the holds are open and easily accessible. “This should enable us to unload cargo through the hatches as would happen with a floating ship alongside a cargo terminal,” Stemm says.

The company was awarded an exclusive salvage contact by the UK government for the British shipwreck last year, which allows Odyssey retain 80 per cent of the salvaged cargo’s value.

Watch: Underwater footage of the SS Gairsoppa wreck: