TOKYO, Oct 1 (Reuters) - Japanese government bond prices rose on Friday as concerns about supply disruptions and the fate of a U.S. stimulus package hit risk assets and after the Bank of Japan refrained from reducing its bond purchases for the quarter. Japanese shares tumbled to one-month lows on mounting fears about supply chain disruptions worldwide and following a delay in a U.S. Congressional vote on the Biden Administration’s flagship spending bills. The Bank of Japan (BOJ) said on Thursday it made no changes in the amount of Japanese government bonds it will purchase in October-December from the previous quarter, a small surprise given some investors had expected it to trim its buying. Benchmark 10-year JGB futures price rose 0.20 point to 151.57, marking the biggest gains since July 5. The 10-year JGB yield fell 2.0 basis points to 0.045% while the 20-year yield fell 2.5 basis points to 0.420%. The 30-year JGB yield fell 1.5 basis points to 0.655%. At the shorter end, the two-year yield fell 1 basis point to minus 0.125% while the five-year yield fell 1.5 basis points to minus 0.100%. Reporting by Tokyo Markets Team; Editing by Subhranshu Sahu Our Standards: The Thomson Reuters Trust Principles.