An improvement in corporate financing has reduced the need for the Bank of Japan's emergency credit programs, BOJ Policy Board member Miyako Suda said Wednesday.

"The need for extraordinary measures is diminishing because corporate financing conditions have improved," Suda said in a speech in Nagasaki. "We can't underestimate the disadvantages" of those policies, she said.

Since the BOJ cut the key overnight lending rate to 0.1 percent in December, it has been buying corporate debt from lenders and offering them unlimited loans backed by collateral to channel funds to companies. Suda, the board's longest-serving member, has been against some of the measures introduced to stem the financial crisis, arguing in January that buying debt from companies was unnecessary.