LONDON >> The yen jumped briefly against the dollar today, putting traders on alert for signs of fresh intervention by Japanese authorities, who likely stepped in the previous day to prop up a currency still close to its lowest in 38 years.

The dollar fell as much as 1% to a one-month low of 157.30 yen, but pared some of those losses to trade down 0.55% at 158.01 yen. The euro was last down 0.2% at 172.28 yen.

Japan’s top currency diplomat Masato Kanda declined to say whether forex market intervention or a rate check was conducted, Jiji Press reported. He did say that the fact that there had been a one-sided, speculative move in exchange-rate fluctuations could not be ignored.

Japan’s Ministry of Finance and the New York Federal Reserve were not immediately available for comment sought by Reuters.

Daily operations data earlier in the day suggested the Bank of Japan (BOJ) may have spent over 3 trillion yen ($18.85 billion) on defending the currency on Thursday, less than three months after it last intervened.

It was not immediately clear what was behind this latest move. Several analysts noted that it bore some of the hallmarks of official buying, but the yen’s strengthening was more modest than Thursday’s, raising some doubt as to whether or not the central bank was behind the trend.

“It could be a modest further round of intervention. I wouldn’t be as confident as yesterday when the move was much bigger,” said Chris Scicluna, head of economic research at Daiwa Capital Markets.

“Given that we have the Japan holiday on Monday, it’s not a bad time for them (Japanese authorities) to enforce the move.

“It’s not the greatest of shifts of the yen so far, so I wouldn’t be overly confident that it’s them,” he added.

NO BREAK FOR THE YEN

Some analysts said the brief bounce in the yen could have been the result of the BOJ making checks with dealers on the exchange rate – often a precursor to buying.

The Nikkei news outlet said earlier today the BOJ had made rate checks during Asia trading hours for the euro/yen currency pair.

With the Japanese currency near its weakest since the mid-1980s, the chances of another round of BOJ buying remain high and Monday’s public holiday in Japan, when market liquidity is likely to be much thinner, could provide a window, analysts said.

“They need to change tactics to keep the market on its toes and show they are serious,” said James Malcolm, head of FX strategy at UBS.

A softer reading of U.S. inflation on Thursday has helped raise the chances of a September rate cut by the Federal Reserve, which could take some pressure off the yen by making it less attractive for investors to trade the large gap between U.S. and Japanese interest rates.

“It wouldn’t surprise me if it were the BOJ, going for a 1-2 punch strategy. Liquidity probably isn’t great so it is a good time, and (Fed Chair) Jerome Powell’s speech on Monday could help things along,” said Kenneth Broux, Societe Generale head of corporate research FX and rates.

Fed Chair Jerome Powell will take part in an interview hosted by the Economic Club of Washington on Monday in which he may offer some kind of signal over whether a September cut might transpire.