The amount of gold bars sold in September through the nationwide retail network of bullion house Tanaka Kikinzoku Kogyo jumped 40 per cent from the previous month and 129 per cent from the same month last year, the company said.

Its sales of platinum bars in September increased 29 per cent month-on-month and 128 per cent year-on-year, Tanaka said.

Tanaka declined to reveal the actual sales volume of both metals.

The World Gold Council has estimated that gold sales in Japan jumped fivefold in September from the previous month to eight to 10 tonnes.

The rise of the yen against the dollar, which lowered the price of imports into Japan, sent private investors flocking to bullion houses, industry sources said.

Retail gold prices offered by Tanaka averaged 1,299 yen pergram in September, down 5.0 per cent from the average retail price in August of 1,368 yen.

Tanaka's retail platinum prices averaged 1,627 yen per gram in September, down by 9.1 per cent from its average retail price in August.

The yen's renewed surge against the dollar this month has given further momentum to gold and platinum purchases for investment purposes, a Tanaka official said.

"Gold bar sales have surged roughly fivefold, while platinum bar sales have nearly doubled," he said. "Investors were very sensitive to the price movements."

Tanaka's retail gold price plunged to 1,172 yen per gram on October 12, its lowest level since August 4, 1995. Its retail platinum price dropped to 1,378 yen per gram on Tuesday, its lowest level since October 23, 1995.

Last week the dollar plummeted 18 per cent against the yen to a low of 111.45 yen. The US currency was trading below 119 yen on Tuesday in Tokyo.

Helped by healthy physical demand, gold bullion prices for delivery in Tokyo have bounced back to apremium of 40 to 50 US cents per ounce over the loco London market, up from parity earlier this month, traders said.

The loco Tokyo platinum premium has advanced to $3 per ounce over the Zurich benchmark from $1.5 earlier this month.