The Japanese yen briefly fell to the 151.97-per-dollar level on Wednesday for the first time since July 1990.

Investors are increasingly selling the yen and buying the dollar. The remarks of a BOJ policy board member are also having an influence. He said in a speech that he thinks the relaxed monetary environment will remain in place for the time being.

The yen has continued to weaken against the dollar since the BOJ monetary decision on March 19.

Japanese Finance Minister Suzuki told reporters he's watching the market closely and has not ruled out any options in terms of a decisive response. Market sources say there is growing sense of caution among traders who are wary of government intervention to keep the yen in check.