Japan's wholesale prices dropped 2.7 percent in October from a year earlier for the 19th straight monthly fall, weighed by lower oil and other commodity prices as well as a stronger yen, Bank of Japan data showed Friday.

The data is a fresh sign that the central bank is facing a difficult challenge to achieve its 2 percent inflation goal, for which the BOJ had already pushed back the time frame five times despite its aggressive monetary easing and a negative interest rate policy. Wholesale prices tend to affect consumer prices.

The index of corporate goods prices stood at 98.7 against the 2010 base of 100, the central bank said in a preliminary report.

Prices of petroleum and coal saw a 7.3 percent fall, and those of nonferrous metals dropped 11.5 percent. Prices of electricity, gas and water marked a 10.8 percent drop while those of chemical products saw a 6.1 percent fall.

Among gainers, scrap prices went up 9.7 percent and prices of business-oriented machinery rose 1.6 percent. Prices of agriculture, forestry and fishery products gained 1.2 percent.

Export prices slumped 9.8 percent and import prices tumbled 14.4 percent, both in yen terms.

Japan's consumer prices fell for the seventh straight month in September, down 0.5 percent from a year earlier, also reflecting lower energy prices, according to government data released last month.