April 29 Reuters The yen jumped suddenly against the dollar on Monday, with traders citing yenbuying intervention by Japanese authorities to try to underpin a relentless tumble in the currency to levels last seen over three decades ago.

The dollar fell sharply to 155.01 yen from as high as 160.245 earlier in the day. Trade sources said Japanese banks were seen selling dollars for yen . It was last fetching 156.21 yen.

Traders had been on edge for weeks for any signs of action from Tokyo to prop up a currency that has fallen 11 against the dollar so far this year. The yen39;s plunge to 34year lows has come despite a historic exit from negative rates last month as traders bet Japanese rates will remain low for some time.

Japan39;s top currency diplomat Masato Kanda declined to comment when asked if authorities had intervened.

I won39;t comment now, Kanda, the vice finance minister for international affairs, told reporters.

Japan39;s Ministry of Finance was not immediately available for comment, with markets in the country closed for a holiday on Monday.

The move has all the hallmarks of an actual BOJ intervention and what better time to do it than on a Japanese public holiday, which means lower liquidity in USDJPY and more Bang for the Bank of Japan39;s buck!, said Tony Sycamore, Sydneybased market analyst at IG.

Bank of Japan Governor Kazuo Ueda told a press conference after a meeting last week that monetary policy does not directly target currency rates,…