A Bank of Japan policymaker said that the central bank should review its yield cap program "at an early stage," noting its high costs, a summary of opinions from a June policy meeting showed Monday.

Some BOJ Policy Board members pointed to the possibility that inflation will not slow as much as expected, remaining above the central bank's 2% target, as the price-setting behavior of Japanese companies has been changing.

As part of its monetary easing, the BOJ has been seeking to keep borrowing costs extremely low through purchases of government bonds. Under its yield curve control program, short-term interest rates are set at minus 0.1%, while 10-year Japanese government bond yields are guided to around zero percent.