Wholesale prices dropped 3.8 percent in March from a year earlier for the 12th straight month of decline, Bank of Japan data showed Wednesday. The falls came amid persistently low prices for crude oil and other commodities.

The index of corporate goods prices stood at 99.6 against the 2010 base of 100, the central bank said in a preliminary report.

For fiscal 2015, the index, which excludes the effects of the consumption tax hike in 2014, slid 3.2 percent from the previous year to 99.0, the lowest since fiscal 2005.

The index marked the second straight year of decline, as tumbling crude oil prices took their toll and demand slumped due to growing concerns about a slowdown in the Chinese economy.

Prices of petroleum and coal dived 23.9 percent in fiscal 2015, which ended in March.

As consumer prices tend to track wholesale prices, the data point to the difficulty facing the BOJ in achieving its 2 percent inflation target.

In March alone, prices of petroleum and coal products marked a plunge of 24.9 percent, the largest among the price categories. Nonferrous metal prices fell 12.5 percent, and those of chemical products 5.6 percent.

Prices of electric power, gas and water saw a marked decline of 13.9 percent.