Prime Minister Shinzo Abe on Friday praised the Bank of Japan for its decision to introduce unprecedented monetary easing measures to fight chronic deflation, while Finance Minister Taro Aso warned the bank could face difficulty achieving its 2 percent inflation goal.

"It is truly bold monetary easing on different levels, sending clear messages to markets," Abe told a Diet committee meeting, adding the BOJ acted "as I had expected."

Abe also said new BOJ Gov. Haruhiko Kuroda is "committed" to achieving their shared goal of 2 percent inflation within around two years.