By Rocky Swift
TOKYO, Aug 20 (Reuters) - Japanese government bonds remained under pressure on Wednesday, with the 20-year debt sliding for an eighth straight day following a lacklustre auction in the previous session.
Yields on Japan's super-long bonds have risen to historic levels in recent months as concerns mount about the country's debt levels and increases in deficit spending by the government.
An auction of 20-year JGBS on Tuesday received bids worth 3.09 times the amount sold, lower than the 3.15 times seen at the previous auction in July.
The 20-year JGB yield JP20YTN=JBTC rose 1.5 basis points to 2.615%, getting closer to the 2.65% level touched last month that was the highest in 25 years. Yields move inversely to bond prices.
"The slight weakness in yesterday's 20-year bond auction is likely to have intensified upward pressure on yields," Mizuho Securities analysts said in a note.
"Looking ahead, with concerns about fiscal expansion remaining strong, the ultra-long-term zone as a whole is likely to face upward pressure."
The benchmark 10-year JGB yield JP10YTN=JBTC was flat at 1.590%. The five-year yield JP5YTN=JBTC fell 0.5 basis point to 1.130%.