By Tetsushi Kajimoto

TOKYO Japan's top currency diplomat Masato Kanda said on Wednesday that authorities won't rule out any options on currencies if speculative moves persist, a comment apparently warning against a sell-off in the yen.

Tokyo's top spokesperson Hirokazu Matsuno made similar comments later in the day, saying the government would take appropriate steps against excessive foreign exchange volatility without excluding any option.

Wednesday's remarks were the strongest since mid-August, when the Japanese currency slid past the key threshold of 145 per dollar. Since then, authorities have stopped firing warning shots, keeping traders guessing on Japan's intervention strategy.

Kanda, vice minister of finance for international affairs, was speaking to reporters after the dollar broke above 147 yen to edge closer to 148 yen overnight, this year's strongest level against the Japanese currency.

The dollar has gained momentum on the view the Federal Reserve may raise rates one more time to cope with persistently solid inflation, while the Bank of Japan is expected to continue powerful easing to stoke demand-pull inflation

"We won't rule out any options if speculative moves persist," Kanda told reporters. "Needless to say, it's important for currency moves to reflect fundamentals."

Matsuno, Japan's chief cabinet secretary, said the government was monitoring the currency market "with a high sense of urgency" and excessive volatility could have a negative impact on the economy by raising uncertainties for companies.

Japanese core consumer price inflation, running above 3% for more than a year, has shown little sign of fuelling sustainable, wage-driven price rises.

(Reporting by Tetsushi Kajimoto; Additional reporting by Kantaro Komiya; Editing by Jacqueline Wong and Christina Fincher)