TOKYO, Aug 2 (Reuters) - Japanese government bonds were narrowly mixed at the start of a new month on Monday, with benchmark 10-year bonds untraded by early afternoon as investors looked to an auction the following day. While the benchmark 10-year JGBs were untraded , the 10-year JGB futures price dipped 0.02 point to 152.28 and the yield on the 20-year JGBs fell 0.5 basis point to 0.630%. Benchmarks for other major maturities were also untraded ahead of Tuesday’s auction of 2.6 trillion yen 10-year JGBs. The Bank of Japan’s bond buying plan for August, announced on Friday, showed its first buying in 10-year JGBs will be on Aug 12. That is the latest date for the BOJ’s buying in that maturity since the BOJ began its massive easing in 2013, said Takenobu Nakashima, chief rates strategist at Nomura. “By refraining from buying for a long period after the auction, the BOJ may be trying to raise the market’s volatility.” Nakashima said. Since mid-July, the 10-year yield has been stuck in a narrow range of 1.5 basis points. Reporting by Tokyo Markets Team; Editing by Rashmi Aich Our Standards: The Thomson Reuters Trust Principles.