June 18 (Bloomberg) - Alumina producers in China, the world's largest consumer of aluminum, may cut production soon in a bid to curb a price decline, Macquarie Group Ltd. said.

Some refiners lowered the cash price of the material used to make aluminum to 3,200 yuan ($465) a metric ton last week, Macquarie said, without giving a comparison figure. Aluminum Corp. of China Ltd. cut prices 17 percent on June 3.

Alumina production in China has outpaced demand this year, forcing Aluminum Corp. and Shandong Chiping Xinfa Group to cut prices. China boosted output 18 percent in the first five months from a year ago, according to the National Bureau of Statistics.

"This spot selling price has left some high-cost producers underwater, especially for refineries based in Shandong province using imported bauxite as a source of raw material supply," Macquarie's Henry Liu and Bonnie Liu said in the e-mailed report.

The marginal cost of refineries in Shandong using imported bauxite could be as high as 3,300 yuan a ton, the analysts said. The price decline will force refineries to put plants on maintenance or reduce output in the coming weeks, Macquarie said.

New alumina projects that started production this year include the 1.6-million-metric-ton a year Guangxi Huayin project, the 400,000-ton Shanxi Yangquan project and the 800,000-ton Guangxi Chiping project, the report said.

Aluminum Corp, also known as Chalco, cut the price of alumina to 3,500 yuan a ton on June 3. The producer is the country's biggest supplier of alumina and aluminum. Aluminum is used in the making of parts in planes and cars.