"So there are many factors which made achieving the 2 percent inflation target or price stability target so difficult and time consuming," Kuroda said in Davos on Friday. "But I think we are finally close to the target."

The yen rose to a 4 1/2-month high versus the dollar after Kuroda's comments, which some traders interpreted as a sign that the BOJ was moving towards an early exit from quantitative easing.

Traders have become sensitive to any sign of a change in monetary policy, because Japan is having its best run of economic growth in more than a decade and some BOJ board members have said it may be necessary to raise interest rates.

The dollar has been falling broadly since the start of the year partly due to speculation the U.S. government prefers a weaker currency, which further complicates the BOJ's task because if the yen strengthens too much, that would push down import prices, making it more difficult to generate inflation.

(Reporting by Stanley White)