TOKYO, April 30 (Reuters) - Japan's top currency diplomat Masato Kanda said on Tuesday that authorities were ready to deal with foreign exchange matters "24 hours", while declining again to comment on whether the finance ministry had intervened to prop up the yen a day earlier.

"Whether it's London, New York or Wellington (hours), it doesn't make a difference," the vice finance minister for international affairs told reporters a day after the dollar tumbled to a low of 154.40 yen from as high as 160.245 in what traders cited as intervention.

He had declined on Monday to confirm the intervention. (Reporting by Makiko Yamazaki Editing by Chang-Ran Kim)