TOKYO, Nov 30 (Reuters) - Japanese government bonds were firm on Monday, supported by bullish euro zone and U.S. debt, although caution ahead of an auction of 10-year maturities capped the market and limited price movements.

December 10-year JGB futures stood unchanged at 148.53. The benchmark 10-year JGB yield was flat at 0.300 percent.

Japan's finance ministry will sell 2.4 trillion yen ($19.56 billion) of 10-year JGBs on Tuesday.

Analysts expect the new 10-year bonds to draw ample demand, helped by index-following investors looking to extend the duration of their bond portfolios towards the turn of each month.

Euro zone government bonds continued to gain, boosted by expectations that the European Central Bank will deliver additional monetary easing this week.

The latest downturn in global equities has also aided safe-haven government bonds such as U.S., euro zone and Japanese debt. ($1 = 122.7300 yen) (Reporting by the Tokyo markets team; Editing by Richard Borsuk)