SINGAPORE, Apr 11, 2012 (Dow Jones) -- Aluminum stocks at major Japanese ports at the end of March had declined 7.3% from a month earlier, a trader at a major Japanese house said Wednesday.

Aluminum stocks totaled 245,100 metric tons, with 126,100 tons in Yokohama, 104,000 tons in Nagoya and 15,000 tons in Osaka. End-February stocks totaled 264,500 tons.

Stocks rose 21.8% from a year earlier, when inventories totaled 201,200 tons.

Japanese demand for aluminum has strengthened slightly since the start of the year due to a modest pickup in the construction sector.

The supply of aluminum in Asia outside China has tightened since the beginning of January due to the movement of large volumes into longterm financing deals, which can keep aluminum off the market for years at a time.

The tighter supply has boosted premiums in Asia, even as demand remains weak in many sectors. Japanese second-quarter contract premiums settled at $115-$127/ton in late March compared with $112-$114/ton in the first quarter.

Three-month aluminum has also firmed since the start of the year, rising around 2.7% to $2,075/ton, reflecting tighter global supply and speculative appetite for industrial metals.