Japan, Asia's second-biggest wheat importer, may increase prices for flour millers by the most since 2008 as weather problems from Australia to North America curb supply, said Nobuyuki Chino, president of Unipac Grain Ltd.

Average costs for milling wheat from the U.S., Canada and Australia gained more than 20 percent in the four months that ended on Dec. 31, government data show. The farm ministry, which sells to flour millers and reviews prices every six months, plans to announce a change next month, based on purchasing costs through February, Shirara Shiokawa, director at the ministry's grain trade division, said Jan. 19. He declined to elaborate.

World food prices climbed 25 percent last year to a record in December on higher sugar, grain and oilseed costs, according to the United Nations. The level exceeded that reached in 2008, when accelerating food prices sparked deadly riots from Haiti to Egypt. Companies such as Japan's largest flour miller, Nisshin Seifun Group Inc., and Yamazaki Baking Co. raised bread and noodle prices when the government increased prices in 2008.