TOKYO, April 13 (Reuters) - Japanese government bonds ticked up on Tuesday, after a re-offering of existing long-dated bonds attracted strong appetite, offsetting worries about further rise in U.S. debt yields. The 10-year JGB yield fell 0.5 basis point to 0.100%. The 20-year JGB yield fell 1 basis point to 0.470% while the 30-year yield dropped 1 basis point to 0.670%. The liquidity-enhancing auction of existing JGBs with 15.5 to 39 years to maturity on Tuesday attracted strong bids, underpinning the market. Benchmark 10-year JGB futures ended up 0.01 point at 151.23, reversing earlier falls. Investors remain wary of further rise in global bond yields on concerns about rising inflation ahead of U.S. consumer price data due later in the day. At the shorter end, the two-year JGB yield fell 0.5 basis point to minus 0.135% while the five-year yield was flat at minus 0.095%.