Central banks need to discuss how to unwind their unconventional policy measures even though the global economy is still in a slump, according to Bank of Japan Policy Board member Atsushi Mizuno.

"Some may argue that it's too early to discuss exit policy when there is a clear negative feedback loop between the economy and finances," Mizuno said in a speech in Tokyo on Thursday, according to remarks published on the BOJ's Web site. "However, it's important for central banks to sufficiently explain the goals of extraordinary policies and their exit strategy to secure credibility."

An unidentified BOJ Policy Board member said at an April 30 policy meeting the central bank should consider how to end untraditional steps should the economy start to recover in line with their forecasts, according to the minutes published last month. Since lowering the overnight lending rate to 0.1 percent in December, the BOJ has also bought corporate and government debt.