The wholesale prices rose 2.1 percent from a year earlier in June for the sixth straight monthly gain on higher oil and steel prices, data from the central bank showed Wednesday.

The increase in corporate prices is expected to lift consumer prices, which have been slow to take off from around zero, even as the Bank of Japan pursues a 2 percent inflation target through aggressive monetary easing.

But the pace of expansion was the same for the third consecutive month, suggesting upward momentum may be leveling off.

"Global month-on-month oil prices have begun to come back down. We'll have to see if gains in other commodities can offset that down the road," a BOJ official said at a news conference.

Oil and coal prices rose 11.1 percent on year as oil exporters continued to cut production, while scrap and waste jumped 20.7 percent after China held back on exports of recycled steel. Iron and steel was up 10.8 percent.

Import prices climbed 11.9 percent partly because the weaker yen pushed up the cost of sourcing oil and natural gas overseas. Export prices were up 5.6 percent.