The Japanese yen tumbled to a near 20-year low against the U.S. dollar on Wednesday, traders said, leading the government here to voice its concerns over such volatility in currency markets.

During Tokyo trading, the Japanese currency plunged to the lower 126 yen mark against the dollar, logging its weakest level since May 2002.

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The yen was moving mainly in the lower and mid-125 yen zone earlier in the day, they said.

Japan's top government spokesperson Chief Cabinet Secretary Hirokazu Matsuno told a press conference that such "rapid currency movements are undesirable."

Matsuno added that "Japan will monitor currency market developments, including the yen's recent depreciation, and their impact on the economy with vigilance."

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The Japanese currency sank as rising U.S. Treasury yields are pushing investors to piling into the U.S. dollar, exacerbating concerns about a widening monetary policy gap between the Bank of Japan and the U.S. Federal Reserve.