A Bank of Japan policy board member said the BOJ should "constrain" the rise in the amount of exchange-traded funds it buys due to the potential impact on its balance sheet, following a March review to make monetary easing sustainable.

BOJ policy board member Hitoshi Suzuki said that while it "certainly is necessary" to continue with ETF purchases as part of the central bank's efforts toward attaining its 2% inflation goal, there will be a large impact on the bank's balance sheet as asset holdings increase. Suzuki was speaking at an online meeting with local business leaders in Yamaguchi Prefecture on Wednesday.

The BOJ has removed a target for buying ETFs at an annual pace of ¥6 trillion ($55 billion) but maintains a ¥12 trillion upper limit for purchases.