Wholesale prices climbed 4.6 percent in June from a year earlier, largely due to higher energy costs, the Bank of Japan said Thursday.

In notching its 15th consecutive month of growth, the index of corporate goods prices came to 106.3 against the 2010 base of 100, the central bank said in the preliminary report.

The April 1 consumption tax hike increased that pace to 4.2 percent in April and 4.4 percent in May. Factoring out the tax hike, the index rose only 1.7 percent to 103.3, compared with 1.5 percent in April and 1.6 percent in May.

In recent months, wholesale prices have fluctuated in a narrower range. A BOJ official said many products are sticking to their current price levels.

Prices for petroleum and coal products were notably higher, up 12.2 percent from the same month a year earlier, on higher crude oil prices that also helped boost prices for chemical products, which rose 2.6 percent.

Gasoline and diesel prices rose amid growing demand, driven by brisk outlooks for the U.S. and Chinese economies, as well as by uncertainty over the security situation in Iraq, the BOJ said.

Import prices, which had pushed up domestic corporate goods prices amid the weakened yen, rose 4.2 percent in yen terms against a downwardly revised 0.6 percent rise in May, signaling the impact of rising crude oil prices. Export prices, meanwhile, rose 2.1 percent in yen terms.