It has inspired numerous expeditions, several mysterious deaths and plenty of books. But 60 years after Nazi officers hid metal boxes in the depths of Lake Toplitz, a new attempt is being made to recover the Third Reich's fabled lost gold.

The Austrian government has given a US team permission to make an underwater expedition to the log-infested bottom of the lake.

Treasure hunters have been flocking to Lake Toplitz ever since a group of diehard Nazis retreated to this picturesque part of the Austrian Alps in the final months of the second world war.

With US troops closing in and Germany on the brink of collapse, they transported the boxes to the edge of the lake, first by military vehicle and then by horse-drawn wagon, and sunk them.

Nobody knows exactly what was inside. Some believe they contained gold looted by German troops throughout Europe and carried back to Germany. Others that they contain documents showing where assets confiscated from Jewish victims were hidden in Swiss bank accounts.

The state company which controls the lake, Bundesforste AG, has signed a contract with Norman Scott, an American treasure hunter, who hopes to solve the mystery.

Later this month Mr Scott will begin a detailed underwater survey of the 107 metre (350ft) deep lake, though there is profound official scepticism that there is anything left to find.

"I really don't know if there is anything down there, but we want to resolve the mystery once and for all," Irwin Klissenbauer, a director of Bundesforste AG, told the Guardian yesterday. "The aim at first is to measure the lake."

He added: "This is a beautiful area. You have heard of Loch Ness. For Austrians this has been a bit like Loch Ness. Lots of people come here. And whether there is gold down there or not, the mystery has been very good for tourism."

Mr Klissenbauer said that under the terms of the deal - which allows the US team to dive for the next three years - any treasure found will be divided between the Americans and the Austrian state.

"Obviously if they recover anything which has an identifiable owner, under Austrian law we have to give it back."

This is not the first time explorers have tried to retrieve the lake's legendary lost gold.

In 1947 a US navy diver became entangled in Lake Toplitz's many submerged logs and drowned.

Then in 1959 a team financed by the German magazine Stern had more luck, retrieving £72m in forged sterling currency hidden in boxes, and a printing press.

The currency, it turned out, was part of a secret counterfeiting operation, Operation Bernhard, personally authorised by Adolf Hitler to weaken the British economy.

Nazis and Nazi sympathisers who had retreated to the Austrian Alps intending to fight a last-ditch guerrilla battle apparently dumped the currency to prevent its discovery.

In 1963 the Austrian government imposed a ban on explorations after another diver, led to the lake by an SS officer, drowned during an illegal dive. More recent expeditions have had mixed fortunes.

In 1983 a German biologist accidentally discovered more forged British pounds, numerous Nazi-era rockets and missiles that had crashed into the lake, and a previously unknown worm.

The last diving team to explore the lake, in 2000, had less luck. After a three-week search in an underwater diving capsule they came away with nothing more than a box full of beer lids, apparently dumped in the lake as a practical joke.

Mr Scott, whose previous expeditions have included a search for a steamer carrying gold coin which sank on the way to Panama, said he was confident he would find "something damn big".

"Until now nobody has explored the lake using hi-tech equipment. We will be the first people to go to the right spot," he told the Swiss news magazine Facts.

Mr Scott, 72, claims to have discovered fresh clues in archives in Berlin and Washington pointing him towards the gold, though he refuses to give details.

Some experts believe he may be right. They point out that the bottom of the lake is encrusted with a thick carpet of logs. Any treasure could be stuck in the mud underneath, they suggest.

"There is a lot of wood down there. We don't know yet whether it is possible to get through it," Mr Klissenbauer said. "You have to remember that the last lot who went down there with a mini U-boat didn't find anything."