TOKYO — Japan's wholesale inflation jumped in May at the fastest annual pace in nine months, data showed on Wednesday, a sign the weak yen was adding upward pressure on prices by pushing up the cost of raw material imports.

The data complicates the Bank of Japan's decision on how soon to raise interest rates, as price rises driven by cost pressures could cool consumption and dampen the chances of achieving the kind of demand-driven inflation it wants to see before further phasing out stimulus, analysts say.

"Consumer inflation may not slow much as wholesale price rises re-accelerate, and energy prices are seen rising sharply towards this summer" as government subsidies to curb utility bills end in June, said Takeshi Minami, chief economist at Norinchukin Research.

"But the BOJ will need to wait for wages to rise and help consumption recover" before raising rates again, he added.

The corporate goods price index (CGPI), which measures the price companies charge each other for their goods and services, rose 2.4 percent in May from a year earlier, BOJ data showed, exceeded a median market forecast for a 2.0 percent gain.

It followed a 1.1 percent gain in April, accelerating for a fourth straight month, with the increase driven by higher prices for utilities, petroleum and chemical goods as well as nonferrous metals, the data showed.

An index measuring the yen-based import goods prices rose 6.9 percent in May from a year earlier, accelerating from a 6.6 percent gain in April, a sign the yen's recent declines were pushing up the cost of raw material imports.

The data will likely be among factors the BOJ board will scrutinize when it meets for a two-day policy meeting ending on Friday. The central bank is widely expected to keep unchanged its short-term interest rate target at a 0 percent to 0.1 percent range.

The BOJ ended eight years of negative interest rates and other remnants of its radical stimulus program in March on the view that prospects for inflation to durably stay around its 2 percent inflation target were heightening.

In the latest projections made in April, the central bank expects core consumer inflation to hit 2.8 percent in the year that began in April, before slowing to 1.9 percent in fiscal 2025 and 2026.

BOJ Governor Kazuo Ueda has said the central bank will hike rates further if it feels more convinced that underlying inflation will stay around 2 percent, as it had projected in April.