The Bank of Japan is ready to implement bold and flexible measures if necessary, Deputy Gov. Hirohide Yamaguchi said Monday after the bank last week announced extra stimulus.

"We will take flexible and bold steps if we judge our policy is insufficient to achieve our policy goal," Yamaguchi said Monday. The bank has no intention of using its policy to directly influence foreign-exchange rates, and sets policy by looking at the impact of currency moves on the economy and prices, Yamaguchi said.

Yamaguchi's comments come after "uncertainty about the global economy" and an inflation rate that is still around zero percent prompted the bank to unexpectedly expand monetary easing last week. The yen's appreciation and a global slowdown have threatened a recovery that has paused, according to the policy statement on Sept. 19.