TOKYO, April 25 (Reuters) - Japanese government bond yields were little changed on Wednesday, firmly capped as the Bank of Japan's debt-purchasing operations offset upward pressure from the ongoing spike in U.S. Treasury yields.

The two-year JGB yield was flat at minus 0.140 percent. The five-year yield inched up 0.5 basis point to minus 0.100 percent and the 10-year yield was unchanged at 0.050 percent.

The BOJ on Wednesday offered to buy 1.34 trillion yen ($12.3 billion) of five- to 40-year JGBs as a part of its regular debt-purchasing scheme.

In addition to tightening supply, Wednesday's JGB-purchasing operations by the BOJ provided some relief for bond investors as the central bank refrained from trimming the amount of debt it had offered to buy.

The U.S. 10-year Treasury note yield extended its overnight rise and touched 3.009 percent on Wednesday, its highest since early 2014.

($1 = 108.9000 yen) (Reporting by the Tokyo markets team, Editing by Sherry Jacob-Phillips)