TOKYO: Japanese government bond yields fell on Monday, with superlong debt yields hitting one-month lows, as investors rushed towards safe-haven assets, as a spike in oil prices due to the Russia-Ukraine war fostered staglation fears.

The 10-year JGB yield fell 1.5 basis points to 0.135% as of 0520 GMT.

The 20-year yield fell 1 basis point to 0.610%, after earlier toucing 0.600% for the first time since Feb. 4.

The 30-year yield fell 0.5 basis point to 0.830%, after touching 0.825% for the first time since Feb. 7.

Russian President Vladimir Putin has vowed to press ahead with the invasion unless Kyiv surrenders, despite severe Western sanctions and the risk of a ban on Russian oil imports.

Moscow calls its actions in Ukraine a "special operation".

It's a textbook risk-off market, but at the same time, "unless there is some new development to worsen the situation, there's no need to rush in and buy to the extent that yields enter a new range compared to last week," said Katsutoshi Inadome, senior bond strategist at Mitsubishi UFJ Morgan Stanley Securities.

"There is some sort of cautious feeling that the market is too expensive." The five-year JGB yield fell 1.5 basis points to minus 0.015%, while the two-year note was untraded, and last yielded minus 0.045%.

Benchmark 10-year JGB futures rose 0.18 point to 151.07, with a trading volume of 14,416 lots.