The Bank of Japan's governor on Friday ruled out pulling the plug on its massive monetary easing plan anytime soon, even as his counterparts overseas move in the opposite direction.

Haruhiko Kuroda's comments come days after the US Federal Reserve hiked interest rates for the third time since December as the world's top economy picks up and the European Central Bank signals it is moving toward turning off the stimulus taps. 

Japan's central bank has not made a significant move for the past five policy meetings, as the economy enjoys its longest run of expansion in more than a decade.

But the growth trend has been shaky and consumer prices remain way below the BoJ's two percent inflation target, a cornerstone of efforts to beat years of deflation and slow growth.

Kuroda insisted the BoJ would leave an 80 trillion yen ($719 billion) annual asset-buying scheme unchanged, along with other policy moves aimed at boosting the world's number three economy.

The central bank now expects to reach its inflation target by 2019 -- four years later than originally planned -- and economists are increasingly doubting if it has the tools to achieve its price promise.

"There is a significant road ahead before we reach the two percent price target," Kuroda told reporters Friday after its latest meeting. 

Frustrated at the Bank's failure to deliver on its inflation pledge, economists and politicians are starting to question the benefit of sustained monetary easing and are calling on the BoJ to explain how it will exit the programme."What is important is that we achieve (that goal) and maintain it. It is not about how long we keep monetary easing in place."

The bank gobbles up vast amounts of government bonds as part of its vast asset-buying plan.

"Politicians certainly are starting to voice doubts about the BoJ's current policies, and we have noted that the BoJ could be forced to exit the current policy even before one percent inflation is achieved, if this clamour picks up," BNP Paribas economist Ryutaro Kono said in a commentary before Friday's decision.

But other analysts said there was little chance of an exit strategy in the near term.

"It's not strange that Kuroda isn't talking about an exit plan when inflation's around zero percent. It's just too early," Daisuke Karakama, chief market economist at Mizuho Bank, told Bloomberg News.

"The problem is that some started to wonder if the BoJ is really thinking about exit at all. That's something Kuroda would want to clarify."