The Bank of Japan's main gauge of inflation slowed to zero, as cheaper oil prices counter Gov. Haruhiko Kuroda's effort to reflate the economy.

Consumer prices excluding fresh food and effects of last year's consumption tax increase were unchanged in April from a year earlier. Including the levy, core prices rose 0.3 percent, the statistics bureau said Friday. That was more than a 0.2 percent gain forecast by economists.

Kuroda is girding for a longer battle to reflate the economy after last month pushing back the timing for achieving a 2 percent target. While he has warned of a temporary drop in prices, he's betting that stronger growth driven by cheaper oil that's weighing on prices now will eventually spur inflation in the world's third-biggest economy.

"Inflation will remain subdued for a while," Tomo Kinoshita, an economist at Nomura Holdings Inc., said before the report's release. "The BOJ will have to expand policy again."

The effects of last year's tax increase lingered in April, adding 0.3 percentage point to core consumer prices, according to the central bank. From May, the impact will drop out of the data.

The yen rose 0.2 percent to 123.74 per dollar at 8:45 a.m. in Tokyo.

Twenty-one of 36 economists see the BOJ boosting stimulus by the end of October, with nine predicting in July, according to a Bloomberg News survey from May 11 to 18. Kinoshita forecasts the BOJ will move in April next year.

Kinoshita forecasts the nation could see 0.2 percent deflation before September, as a 46 percent fall in oil from last year's peak in June pushes down consumer prices. All but two of 29 economists surveyed from March 5 to 12 said there was a chance that core consumer prices will decline at some point this year.

The BOJ refrained from increasing stimulus last week, with Kuroda signaling more optimism on the economy and confidence that inflation remains on track for 2 percent, a goal that he pushed back on April 30 by as much as six months to around the half-year through September 2016.

"We aren't thinking about any specifics for additional measures now as we expect the price trend will steadily improve," Kuroda said on May 22.

The BOJ is counting on rising demand, tighter supply and expectations for price increases to drive inflation. There's some evidence that households see living costs are set to rise.

Eighty-nine percent of consumers in a Cabinet Office survey earlier this month said they expect prices to rise in the year ahead. Chocolate maker Morinaga & Co. and Yamazaki Baking Co. said Tuesday they will raise the price of their products.

The government and the central bank both raised their assessments of consumer spending this month, encouraged by resilience in private consumption growth that helped drive faster-than-forecast growth in the first quarter.

Gross domestic product expanded an annualized 2.4 percent in the three months through March, also getting a lift from a buildup in inventories that threatens to weigh on industrial production in the months ahead.