TOKYO, May 26 (Reuters) - Japanese government bonds were unchanged on Wednesday, with investors turning cautious ahead of a 40-year bond auction while drawing support from firmness in U.S. peers on easing concerns about inflation. All major benchmark maturities were flat, with the 10-year yield at 0.070%, the 20-year yield at 0.440% and the 30-year JGB yield at 0.670%. The 40-year JGB yield was flat at 0.725% ahead of Thursday’s auction of that maturity. Benchmark 10-year JGB futures rose 0.02 point to 151.52. In the United States, the benchmark 10-year Treasury yield fell to a two-week low of 1.56%, even as Federal Reserve policymakers began to acknowledge they are closer to debating when to pull back some of their crisis support. (Reporting by Tokyo Markets Team; Editing by Ramakrishnan M.)