The treasure trove is thought to be spread around 28 ships lying at the bottom of the Atlantic - some at depths of more than 500ft.
So far, the operation has remained a secret for fear of starting "a gold rush similar to Klondike", but Designaztec, the British salvage firm leading the search, said yesterday that it had found the first three ships. The team has located diamonds, sapphires, gold coins and other artefacts including an FA Cup winner's medal dating from 1900 and is now due to start a 46- day pounds 2m salvage operation.
The operation is the result of 25 years of research and, if the company is proved right, the haul of gold could be enough to flood world markets and send the price of bullion tumbling. Gold is now worth 60 times its value in the First World War.
Terrance Playle, of Designaztec, said: "It is well documented that Britain and its colonies shipped many thousands of tons of gold to America during the wars to pay for armaments and to safeguard assets. We believe that our research both identifies the gold carriers that were sunk and marks their precise position on the sea-bed."
The team is using a diving vessel called Rockwater I, which was used to film the remains of the Titanic and is one of the most sophisticated dive ships in the world.
It has been commissioned at a cost of pounds 90,000 a day and is now sitting above Hesperian, a British ship sunk by a U-boat in 1915 on its way from Liverpool to Canada. "We have 12 divers working on Hesperian," said Mr Playle. "We have records that show it was carrying a substantial quantity of bullion and have already recovered a quantity of loose diamonds."
The other bullion carriers that have been located by Rockwater I are the Arabic, sunk in 1915 on the way to New York, and the Empress of Britain which was sunk in 1940.
Any gold and other treasures which are recovered from the wrecks will be brought back to a British port and handed to the Receiver of Wrecks. It must then technically be held for a year and a day to allow any claims to be made.
"We do not say that what we bring back belongs to us but we expect to be paid a very high reward for recovering it," said Mr Playle. "The exact numbers will be calculated by the receiver - we anticipate a cut of between 30 and 60 per cent."Reuse content