The Bank of Japan's unexpected desicion to expand its annual asset purchases - its main tool to spur higher inflation - could have broad implications for markets, such as by benefiting Japanese exporters by knocking the yen further down against the US dollar, the Wall Street Journal said on Friday.

It noted that the move was in the opposite direction from the Federal Reserve, the US central bank, which on Wednesday ended its six-year long quantitaive easing programme.

It added that the move also underscores how Prime Minister Shinzo Abe 's economic revival plan has gotten off track since a national sales tax increase in April this year damped consumer spending, sending repercussions across the world's third-largest economy.

The BOJ announced Friday it would expand its annual asset purchases to 80 trillion yen from the previous target range of 60 trillion to 70 trillion yen, mostly by buying more Japanese government bonds, cementing its status as the single largest investor in JGBs.

The BOJ also said it would triple the pace of its purchases of stock and property funds.

Significantly, the decision by the central bank's nine policy board members was split with five members in favor and four members opposed. It was the first split vote on policy since Gov. Haruhiko Kuroda took helm of the central bank in March last year, the Journal noted.