Bank of Japan Policy Board members said purchases of exchange traded funds and real estate investment trusts could increase transactions by supporting investor sentiment, minutes of their Oct. 4-5 meeting showed Tuesday.

"Some members said that while the amount of purchases might be small, the bank's purchase would produce positive effects as a catalyst in promoting more active transactions in their markets and more risk-taking activity in the overall economy," according to minutes.

The BOJ unexpectedly lowered its benchmark interest rate at the meeting and pledged to spend ¥5 trillion to buy assets including government bonds and corporate debt.

Gov. Masaaki Shirakawa said last week that bolstering that fund will be a "probable option" should the BOJ need to provide additional monetary stimulus.