Bank of Japan Gov. Haruhiko Kuroda said recent movements in Japan’s currency have been on the rapid side, in his clearest warning signal yet against sharp changes in yen levels.

"If you look at moves in foreign exchange rates over the longer term such as the past decade, fluctuations have gotten smaller but as pointed out, the recent moves in foreign exchange rates seem somewhat rapid,” Kuroda said in response to questions in parliament Tuesday.

Following the remarks the yen strengthened to ¥122.38 against the dollar from around ¥122.86 earlier in the morning session.