The Bank of Japan pledged to adjust its unprecedented stimulus program as needed after a jump in bond yields that highlighted risks linked to policymakers' campaign to revive the world's third-largest economy.

BOJ Gov. Haruhiko Kuroda told reporters in Tokyo that the central bank will conduct its debt purchases in a flexible manner, and that the recent volatility in government securities isn't yet affecting the economy. He spoke after the BOJ board affirmed its plan to double the monetary base in two years as it seeks to end 15 years of entrenched deflation.

The biggest surge in government debt yields in five years threatens to undermine the BOJ's stimulus, with companies including steelmaker JFE Holdings Inc. pulling bond sales amid the tumult. The prospects of a growth rebound and the emergence of inflation has contributed to sending the rate on 10-year bonds up more than a quarter percentage point in two weeks.