TOKYO, April 19 (Reuters) - Yields on long-dated Japanese government bonds rose on Friday after the Bank of Japan (BOJ) trimmed the amount of debt it offered to buy at a regular market operation.
Gains in Tokyo shares, which were up nearly half a percent by early afternoon trade, also weighed on JGB prices.
The BOJ on Friday offered to purchase 160 billion yen ($1.43 billion) of 10- to 25-year JGBs, down from 180 billion yen at the previous operation last week.
The central bank also trimmed its purchase of 25- to 40-year JGBs, reducing the amount it offered to buy to 40 billion yen compared to 50 billion yen previously.
The BOJ often tweaks the amount of JGBs it purchases at its regular operations as part of its yield curve-controlling scheme.
The benchmark 10-year JGB yield gained half a basis point to minus 0.025 percent.
The 20-year yield rose one basis point to 0.390 percent.
The 30-year yield climbed two basis points to 0.575 percent while the 40-year yield advanced 2.5 basis points, to 0.605 percent.
Ten-year JGB futures were 0.01 points higher at 152.55, with a trading volume of 27,405 lots by early afternoon trade.
$1 = 111.92 yen Reporting by Tokyo Markets team; Editing by Shreejay Sinha