TOKYO, Oct 30 (Reuters) - Yields on Japanese government bonds rose on Friday due to worries about a dip in investor demand after a weak auction of seven-year Treasuries in the previous session.

Yields also edged higher after a Bank of Japan government debt buying operation failed to support prices in a sign that investors are nervous about holding long positions before the U.S. presidential election on Nov. 3, dealers said.

Benchmark 10-year JGB futures fell 0.09 point to 151.93, with a trading volume of 17,216 lots.

At the short end of the curve, the two-year JGB yield rose 0.5 basis point to minus 0.125%, which is the highest since Sept. 3.

The five-year yield rose 1 basis point to minus 0.100%.

The 10-year JGB yield rose 0.5 basis point to 0.030%, but the 20-year JGB yield was flat at 0.405%.

The 30-year JGB yield rose 1 basis point to 0.635%.

At the long end of the curve, the 40-year JGB yield rose 0.5 basis point to 0.660%. (Reporting by the Tokyo markets team; Editing by Rashmi Aich)