Japan aluminium stocks rise for first time in 9 months

Aluminium stocks held at three major Japanese ports climbed for the first time in nine months in May due to an increase in imports and softer demand at home.

The increase comes as global aluminium producers and Japanese buyers negotiate premiums for July-September primary metal shipments.

Japan is Asia's biggest importer of aluminium and the premiums it agrees to pay each quarter over the London Metal Exchange (LME) cash price set the benchmark for regional primary metal shipments.

"The rise in inventories may be due to higher imports after Japanese trading houses trimmed purchases of the metal in the January-March quarter," a source at a trading house said on Thursday.

"Slower demand from the manufacturing sector such as automobile makers in the Golden Week long public holiday in early May may also be behind the hike in stocks, although the increase was not that big," the source said.

Japanese buyers cut purchase volumes of aluminium ingots in January-March in a bid to slash inventories, importing 101,810 tonnes a month on average over the period. Imports rose to 128,429 tonnes in April, according to official trade data.

Aluminium stocks at three major Japanese ports stood at 337,200 tonnes at the end of May, up 3.8 percent from a month earlier, trading house Marubeni Corp said on Wednesday.

Marubeni collects data from the ports of Yokohama, Nagoya and Osaka.