Japan's core consumer prices for items excluding fresh products rose 2.4 per cent on-year in July, the highest in more than seven years and marking four straight monthly gains of more than two per cent, government data showed on Friday.

While energy prices continued to mount, the speed of the increase has slowed, according to data released by the internal affairs ministry, which matched market expectations.

The figure is the highest since December 2014.

Prices have increased for nearly 80 per cent of non-fresh food products, NLI Research Institute said, predicting that core CPI may touch 2.9 per cent by October.

NLI Research Institute predicts that core CPI may touch 2.9% by October

"Until now, sharp rises in energy prices, triggered by rising crude oil costs, drove up the core CPI. But the main cause is shifting to food," NLI said.

Central banks worldwide are hiking interest rates to fight soaring inflation, but the Bank of Japan sees recent price rises as temporary, so has kept its ultra-loose monetary policy in place.

This has pushed the yen lower against the dollar in recent months, making imported products more expensive.

"For the time being, a lot of price hikes can be attributed to the yen's depreciation," Dai-ichi Life Research Institute said.

BoJ governor Haruhiko Kuroda has said he is committed to the current policy, which aims to create sustainable growth through rising corporate earnings, growing wages and sustained inflation of around two per cent.