The Japanese finance minister, Sadakazu Tanigaki, has warned that excessive movements in the currency market could hurt the Japanese economy, prompting caution from those investing in Asia's largest economy.
The warning comes after the yen rose over five per cent against the dollar in just over two weeks, reaching an eight-month high.
Speaking at a news conference in Tokyo, Mr Tanigaki said: "Excessive and disorderly movements in exchange rates are undesirable because they may hurt economic growth."
"Exchange rates should reflect fundamentals – based on that thinking, which is also the thinking of the G7, we will continue to monitor the market carefully," he added.
However, Mr Tanigaki refused to comment on the possibility of government intervention to prevent the gap between yen and dollar valuation growing any greater.
The concern is that the high price of the yen could hurt exports from Japanese companies, something that would cause investors to become less enthusiastic about investing in Japanese businesses.
Japan has seen promising economic growth in recent years, following the problems of the late 90s when the bubble burst on what was regarded as the economic miracle of the Japanese economy.