TOKYO, Nov 12 (Reuters) - Japanese government bond futures surged to a three-week high on Thursday after an auction of five-year debt drew solid demand, helping allay recent market concerns over Japan's fiscal situation.

December 10-year futures 2JGBv1 were up 0.48 point at 138.34 after hitting 138.38, the highest since Oct. 23.

The bid-to-cover ratio, a gauge of demand, at the five-year auction climbed to 3.7 from 2.17 at the previous tender in October. TENDER01