Japan's top currency diplomat Masato Kanda said on Thursday he was concerned about recent exchange rate moves that have become dominated by speculation and were out of line with fundamentals, Jiji news agency reported.

Kanda also said foreign exchange moves since the beginning of the year have been "very big", impacting households, according to Jiji.

The remarks were the strongest to date from Japanese authorities warning against the yen's recent sharp declines against the dollar.

Kanda, who is vice finance minister for international affairs, said he was not in a position to comment on whether authorities had intervened in the market, Jiji Press reported.

The comments came after the dollar fell as much as 2.5% against the yen following weaker-than-expected U.S. CPI data.

Finance ministry officials have not responded to Reuters request for comment.

Japanese authorities have recently made it standard practice to not confirm whether they have intervened in the currency market or not.

(Reporting by Chang-Ran Kim and Leika Kihara; Editing by Toby Chopra)