By Makiko Yamazaki and Leika Kihara
TOKYO (Reuters) -Japan's top currency diplomat said on Friday authorities would take action as needed in the foreign exchange market, resuming his jawboning after the yen's spike overnight raised market speculation about currency intervention.
Bank of Japan (BOJ) data released later on Friday suggested Japan may have spent up to 3.57 trillion yen ($22.4 billion) intervening in the foreign exchange market to prop up the sagging currency.
Masato Kanda, who is vice finance minister for international affairs, declined to comment on whether authorities had intervened in the currency market to prop up the yen, but told reporters recent yen moves were out of line with fundamentals.
Chief Cabinet Secretary Yoshimasa Hayashi also told reporters on Friday that authorities were ready to take all possible action on exchange rates.
The remarks on the yen break the recent silence among Japanese officials, who have refrained from commenting on their readiness to intervene as analysts question the effectiveness of jawboning in stopping sharp yen declines.
"I've found recent big currency moves strange, from the perspective of whether they were in line with fundamentals, and it would be highly concerning if the excessive volatility, driven by speculation, pushes up import prices and negatively affect people's lives," Kanda said.
"Currency interventions should certainty be rare in a floating rate market, but we'll need to respond appropriately to excessive volatility or disorderly moves," he added.
Finance Minister Shunichi Suzuki also told a regular news conference on Friday that rapid, one-sided moves in the foreign exchange market were undesirable.
The yen surged nearly 3% on Thursday in its biggest daily rise since late 2022, shortly after U.S. consumer price figures revived market expectations the Federal Reserve will cut interest rates in September.
GUESSING GAME
Some local media had attributed the yen's abrupt spike to a round of official buying to prop up a currency that has languished at 38-year lows. The dollar climbed back to 158.88 yen on Friday, after falling to as low 157.40 yen on Thursday.
"Japan likely intervened as otherwise, the yen won't move that much so suddenly," Takahide Kiuchi, an economist at Nomura Research Institute, said of the yen's overnight jump.
"Japan's past interventions were made when the yen was plunging, some of which weren't necessarily effective. This time it worked because authorities took action just when the weak-yen trend was turning around," he said.
Meanwhile, the Nikkei newspaper reported that the BOJ conducted rate checks with banks on the euro against the yen on Friday, citing several sources.
Finance minister Suzuki declined to comment on whether authorities made rate checks, which are seen by traders as a precursor to actual yen-buying intervention.
Japanese authorities have recently made it standard practice to not confirm whether they have intervened in the currency market or not.
Tokyo spent 9.8 trillion yen ($61 billion) intervening in the foreign exchange market at the end of April and early May, official data showed, after the Japanese currency hit a 34-year low of 160.245 per dollar on April 29.
Back then, authorities were suspected to have intervened in several stages to create a buffer to defend the 160 mark against the dollar.
If Tokyo were to have stepped in on Thursday, it would have been more aimed at accelerating the yen's rebound against the dollar that occurred shortly after the weaker-than-expected U.S. inflation data.
Some analysts doubt whether intervention will work to reverse the weak-yen tide.
"You can't change the market's trend with intervention. Whether the market's phase would change depends largely on fundamentals," said Tsuyoshi Ueno, an economist at NLI Research Institute.