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* Nov core CPI up 0.9 pct yr/yr vs f'cast 1.0 pct
* Nov core-core CPI up 0.3 pct yr/yr vs +0.4 pct in Oct
* Data underscores BOJ's challenge in hitting price goal
TOKYO, Dec 21 (Reuters) - Japan's annual core consumer inflation slowed in November, reinforcing market expectations the central bank will hold off on whittling down stimulus for a prolonged period as prices remain distant from its target.
The nationwide core consumer price index (CPI), which strips away the effect of volatile fresh food costs, rose 0.9 percent year-on-year in November, slowing from a 1.0 percent gain in October. It compared with a median market forecast for a 1.0 percent increase.
The so-called core-core CPI, which strips away the effect of both fresh food and energy costs, increased 0.3 percent in November from a year earlier, slowing from the previous month's 0.4 percent gain.
The data underscores the challenge the Bank of Japan faces in achieving its elusive 2 percent inflation target. Rising economic risks cast doubt on its argument that maintaining its current level of stimulus is enough to reach its price goal.
Stubbornly soft inflation has dashed the BOJ's hopes that solid economic growth would translate into higher prices, forcing it to maintain its huge stimulus despite unwelcome side-effects such as the erosion of financial institutions' profits from years of near-zero interest rates.
The central bank maintained its ultra-loose monetary programme at a rate review on Thursday, as simmering Sino-U.S. trade tensions, softening global demand and volatile markets cloud the outlook for the world's third-largest economy. (Reporting by Leika Kihara Editing by Shri Navaratnam)