In London one of the UK's leading gold bar and coin merchants ATS Bullion has experienced unprecedented demand over the past few days.

Nervous investors are shunning banks in the current financial crisis, and putting their savings into one of history's most tangible representations of wealth: gold bars and coins. Demand is so high among the world's wealthy that suppliers are seeing their stocks dramatically depleted.

"It's notable that there has been an increase in interest in gold generally," according to Justin Oliver, senior investment manager at Collins Stewart, who advises worried investors about where to put their money. "Gold is still viewed as a safe haven in times of crisis".

Just last week the US Mint, which has been responsible for ensuring an adequate supply of American coinage since 1792, was forced to halt sales of the "American Buffalo" solid 24 carat gold coins because it was running out of supplies. It had already needed to ration supplies of the 22 carat "American Eagle" alternative by starting an allocation programme which limits the number that can be sold at any given time.

The price of both one ounce coins was also lower than the price of an ounce of gold on the open market at the time, making them incredibly tempting to investors looking to make a quick return. Having broken through the $1,000 (£562) barrier earlier in the year, the gold price has retreated and is now trading at around $880 an ounce. The 2007 American Eagle one ounce coin, however, was going for at $789.95 while the 2006 Buffalo coin cost $800. The prices of the current - 2008 - editions are $1,119.95 and $1,199.95.

A spokeswoman for the US Mint said sales of 24 ounce coins are up 34% this year, with 164,000 snapped up already.

"We are now working diligently to build up our inventories and hope to be able to re-sell the coins shortly," she added.

In London, meanwhile, one of the UK's leading gold bar and coin merchants ATS Bullion has experienced unprecedented demand over the past few days at its shop next door to the Savoy Hotel.

"There has been enormous demand," according to managing director Sandra Conway. "There are very few sellers of physical gold and we have had queues of people today."

"We have got gold in stock but there have been some shortages, especially of Krugerrands."

Named after Paul Kruger, who headed up the Boer resistance to the British in the 19th century, Krugerrands were first minted in South Africa in 1967. Although it was illegal to import them into the UK during the 1970s and 1980s, because of apartheid, they are now one of the most widely circulated gold coins. As such the price of the one ounce coins tends to track the gold price to within a few percentage points, making them a perfect vehicle for investors.

The World Gold Council, formed and funded by the world's leading gold mining companies, has seen a clamour for gold from across the world. Some refineries are believed to be having trouble keeping up with demand.

"We are seeing a large amount of buying in the retail sector, in the form of bars and coins," said a spokesman. "But there is also heavy buying in gold-backed securities".

Gold is traded in the form of securities on stock exchanges in Australia, France, Hong Kong, Japan, Mexico, Singapore, South Africa, Switzerland, Turkey, the UK and US. Called exchange traded commodities or exchange traded funds (ETFs), they track the gold price almost perfectly and are actually backed with physical gold.

They appeal to investors because they do not require the actual storage of gold by the buyer and ETFs are traded in a number of currencies while the gold price is set in dollars which can be an advantage, especially to European investors.

The World Gold Council reckons such securities represent about 38% of all the world's investment in gold. There are now 1088 tonnes of gold invested in these markets with strong buying reported over the past few days.