A major battle may well have started between the office of Prime Minister Shinzo Abe and the Finance Ministry — the most powerful bureaucracy in Japan — as the deadline approaches for deciding whether to raise the consumption tax rate from the current 8 percent to 10 percent from Oct. 1, 2015, as provided by law, a veteran economist says.

The fight, he adds, could be the fiercest of its kind in Japan's postwar history.

Abe has so far remained noncommittal, saying he will first wait for the release of updated statistics on the nation's gross domestic product (GDP) for the July-September quarter and then make up his mind in early December, shortly before the government begins drafting the budget for fiscal 2015.