TOKYO, May 11 (Reuters) - Japanese government bond prices were mostly lower on Wednesday, as caution took hold ahead of an upcoming 30-year debt auction.

Japanese shares also extended gains amid a broad reversal in the yen's recent appreciation, reducing investor demand for government bonds.

The benchmark 10-year yield was little changed at minus 0.100 percent. The 20-year yield rose 1.5 basis points to 0.275 percent and the 30-year yield was up a basis point at 0.320 percent.

Japan's finance ministry will offer 800 billion yen ($7.35 billion) of 30-year JGBs on Thursday.

JGB losses were limited on Wednesday in the shorter-dated maturities as the Bank of Japan conducted a regular debt-buying operation earlier in the day as a part of its extensive easing scheme.

($1 = 108.8400 yen) (Reporting by the Tokyo markets team; Editing by Jacqueline Wong)