Bank of Japan Governor Haruhiko Kuroda said the central bank was watching exchange-rate moves carefully as they affect the economy and prices. But he added that currency policy, including whether and when to intervene in the market, falls under the jurisdiction of the Ministry of Finance (MOF).

"The BOJ would not do something for exchange-rate stability" as doing so is the responsibility of the MOF, Kuroda said, when asked by an opposition lawmaker in parliament about recent yen rises.

Kuroda also said the central bank would "swiftly" consider easing monetary policy if the economy lost momentum towards achieving its 2 percent price target.

He also told parliament that a further escalation in the U.S.-China trade friction could inflict significant damage on the global economy by hurting trade activity and business sentiment.