TOKYO, Oct 15 (IFR) - Japanese government bond yields slipped on Wednesday, with the 10-year yield falling to 1 1/2-month low, in smpathy with the fall in global bond yields on concerns over a slowdown in the world economy.

The 10-year JGB yield dipped 0.5 basis point to 0.485 percent, matching a trough hit in late August. The 20-year yield also fell 0.5 basis point to 1.335 percent .

The immediate focus is on an ongoing auction of 30-year JGBs, the results of which will be due at 12::45 p.m. (0345 GMT).

JGB players widely expect the auction to go relatively smoothly, supported by dealers' short-covering, and on expectations of buying by the Bank of Japan.

(Reporting by Masatsugu Hisatsune)