TOKYO, Jan 12 (Reuters) - Japanese government bond prices gained slightly on Thursday, supported by a rise in Treasuries and as Tokyo stocks retreated to two-week lows following U.S. President-elect Donald Trump's news conference.
The benchmark 10-year JGB yield was down half a basis point at 0.050 percent and the 40-year yield declined 1 basis point to 0.890 percent.
The Bank of Japan also conducted a regular debt-buying operation on Thursday and supported longer-dated JGBs.
Prices on Treasuries rose with yields falling to one-month lows overnight following a strong 10-year note auction and as Trump's news conference contained no details on tax cuts and infrastructure spending.
The Nikkei was down 1.3 percent, as the dollar slumped against the yen in the wake of the slide in Treasury yields. (Reporting by the Tokyo markets team; Editing by Jacqueline Wong)