Salvagers claim to have found the world's richest wreck - a British ship sunk by a Nazi submarine while laden with a £2.6 billion cargo that included gold, platinum and diamonds.
In a project shrouded in secrecy, work is due to start on recovering the cargo, which was being transported to the United States to help pay for the Allied effort in the Second World War.
The scale of the treasure trove is likely to unleash a series of competing claims from interested parties. Salvage laws are notoriously complex and experts say there could be many years of legal wrangling ahead.
In order to protect its find until the cargo is brought to the surface, the company that located the wreck has not released the name of the vessel or its exact location, but has given the ship the code name "Blue Baron".
It says the merchant ship, which had a predominantly British crew, had left a European port, laden with goods for the US Treasury under the Lend-Lease scheme, whereby the American government gave material support to the Allied war effort in exchange for payments.
The Blue Baron first sailed to a port in South America, where it unloaded some general cargo, before continuing north in a convoy, heading for New York.
However, the company claim it was intercepted by German U-boat U87 and sent to the bottom by two torpedoes in June 1942, with the loss of three crew members. Their nationalities are not known.
Sub Sea Research, a US-based marine research and recovery firm, claims it has now located the wreck under 800ft of water about 40 miles off Guyana.
Greg Brooks, the company's founder and co-manager, said: "This British freighter had an extremely valuable cargo and we decided there wasn't a lot of point in leaving it at the bottom of the sea. This will definitely be the richest wreck ever."
Until now, historians have not credited U87 with sinking any vessels in that area in June 1942 and it was thought to have been operating further north in the Atlantic.
However, Sub Sea Research claims to have located the submarine's log book which prove it did sink the "Blue Baron", as well as documents from the port of origin, the US Treasury and the Lend-Lease programme giving clues as to what was on board.
A picture of the Blue Baron supplied to The Sunday Telegraph by the company shows it is a tramp steamer and her funnel appears to resemble those of the shipping line Hogarth and Co, of Glasgow, whose ships were known as Hungry Hogarths.
Tantalisingly, the names of its ships all began with the word Baron - indicating that the Blue Baron could be one of them. However, none of the fleet's 17 ships lost in the war appear to have been sunk in this area in June 1942.
The picture also resembles Port Nicholson, a steamer sunk by U87 in June 1942 but 2,000 miles north of Guyana off Cape Cod. Sub Sea Research insists that the Port Nicholson is not the Blue Baron.
It claims that the Blue Baron's cargo included at least ten tons of gold bullion, 70 tons of platinum, one a half tons of industrial diamonds and 16 million carats of gem quality diamonds.
In addition, there were several thousands tons of tin and a few thousand tons of copper ingots. Although the tin and copper may have lost some value after years on the sea bed, the precious metals and diamonds would not have done so.
The haul's total worth is calculated at £2.6 billion at today's prices, according to the firm.
Captain Richard Woodman, author of The Real Cruel Sea, a history of the merchant navy in the Second World War, said: "A lot of merchant ships did have to carry valuable cargoes like this.
Any heavy materials had to go by sea. It was the only way to get from A to B. There would have been an element of protection for them, but in the end it is just the coincidence of war that a ship happens to stop a torpedo."
A 220ft salvage vessel is currently being equipped to recover the cargo. It is due to sail next week from the US state of Louisiana to the wreck site, which lies in international waters.
The company has refused to reveal which government sent the valuables to the US or which was the Blue Baron's final port of call in Europe.
It is thought much of the treasure could be Russian, although part, including the diamonds, may have been British.
Britain and Russia were the two main beneficiaries of the Lend-Lease scheme, under which the US provided $50 billion of supplies - equivalent to $700 billion (£510 billion) in today's money.
Although explorers are permitted in law to stake claims on items they recover from the seabed, the original owners can make counter claims.
Sub Sea Research was forced to go public with its discovery when it filed a claim on the treasure in a US federal admiralty court, to which no counter claims have been lodged so far.
Mr Brooks said: "No one has stepped forward to make a claim yet, probably because the government that lost it does not realise.
"We are trying to keep it as quiet as possible until we have it in our possession. We think the possessions on board may belong to more than one country.
"I know for a fact that everyone possible will try to take it from us, but we are doing everything by the book. I think the worst case scenario, under salvage law, is that we would get 90 per cent of it. But we are trying to go for 100 per cent."
Mike Williams, an expert in salvage law at Wolverhampton University, said the Government which had owned the cargo would retain a strong claim on it.
He said: "Both Britain and Russia transhipped large quantities of precious goods to the US to pay for their war effort. It would be unlikely the salvors would be able to keep it all.
"The real winners will be the lawyers. There is a marine lawyers' saying that treasure is trouble."
© 2009 - Telegraph.co.uk