Former head of the U.S. Federal Reserve, Ben S. Bernanke, endorsed the Bank of Japan's extraordinary easing measures to break free of persistent deflation and underlined the importance of coordinating monetary policy with fiscal stimulus.

"Despite improvement in the Japanese economy, I think there's still a strong case for the Bank of Japan to continue to pursue its target (of 2 percent inflation)," the former Fed chairman said in a speech Wednesday at the BOJ's Tokyo headquarters.

Since April 2013, Japan's central bank has maintained a policy involving an aggressive asset purchase program and later negative interest rates, hoping to reach its target sometime around fiscal 2018.