Wholesale prices rose in September from a year earlier for the seventh straight month, posting the sharpest gain in more than 13 years, the Bank of Japan said in a preliminary report Thursday.
The prices, measured by the central bank's corporate goods price index, registered 96.6 against the 2000 base of 100, up 1.8 percent from a year before. It was the largest rise since February 1991, when wholesale prices also climbed 1.8 percent.
The index is designed to gauge movements in prices of goods traded among companies.
It rose 0.2 percent in March for the first gain since July 2000, and the scale of the rise has increased every month since then, fueling optimism that Japan's economy might be pulling out of deflation.
But consumer prices remain in negative territory.
September's rise in wholesale prices stemmed partly from a 16.9 percent jump in prices of petroleum and coal products, which include gasoline and diesel oil, as crude oil prices soared on the global market.
Chemical products prices rose 3.9 percent and steel prices surged 16 percent, reflecting their strong demand in China and other Asian countries.