Aluminium stocks held at three major Japanese ports rose for an eighth straight month to hit a record high at the end of November on rising imports and softer demand at home.
Aluminium stocks held at Yokohama, Nagoya and Osaka rose 14 percent in November from a month earlier to 378,000 tonnes, the highest level in data going back to April 2000, trading house Marubeni Corp said on Friday.
"An increased number of aluminium ingots are coming to Japan to look for buyers amid slowing demand elsewhere in Asia as China steps up exports of cheaper aluminium products to neighbouring countries," said a Tokyo-based trader, who declined to be named.
Japan's import of aluminium ingot rose 16 percent to 1.43 million tonnes in the January-October period from the same period in 2013, according to the country's trade data.
The inventory increase also reflects slowing demand in Japan as consumption and exports remain weak, another trader said.
The world's third-largest economy has unexpectedly slipped into recession. Gross domestic product (GDP) shrank an annualised 1.6 percent in the July-September quarter after plunging 7.3 percent the previous quarter following a rise in sales taxes that clobbered consumer spending.
Recent economic data have also remained weak with falling machinery orders and inflation expectations, depressed sentiment in a government "economy watchers" survey and feeble capital-spending plans.