JGBs slip ahead of 10-year sale, disappointment with BOJ

* 10-yr yields poised to end month with recent range intact

* 0.8 pct coupon expected at Thursday's 10-yr auction

TOKYO, Oct 31 (Reuters) - Japanese government bonds slipped on Wednesday, reflecting continued disappointment over the Bank of Japan's easing measures and on positioning ahead of Thursday's 10-year sale.

The Ministry of Finance will offer 2.3 trillion yen ($29 billion) worth of 10-year notes on Thursday. Market participants expect a reopening of the number 325 issue with a coupon of 0.8 percent.

``We think it is safe to continue long positions within 0.75-0.8 percent range. Yet auction results could still present surprises because of uncertain market conditions,'' strategists at RBS Japan Securities said in a note to clients.

Primary JGB dealers warned the finance ministry last week of the growing risk of a ratings downgrade over a political standoff preventing the government from passing legislation it needs to seel bonds to fund this fiscal year's budget.

JGBs also came under pressure as Japanese stocks advanced on Tuesday on relief that some firms did not cut their full-year earnings guidance as feared. The Nikkei rose 1 percent to end the month 0.7 percent higher, its third straight monthly gain.

``Since we have a rebound today, it's pushing the yield high in JGBs. But it's also disappointment with the BOJ,'' said Maki Shimizu, senior strategist at Citigroup Global Markets Japan.

On Tuesday, Japan's central bank said it will increase its asset purchasing programme by 11 trillion yen ($138 billion) to 91 trillion yen as expected. The meeting took longer than usual, raising market hopes that the BOJ was considering steps beyond those already expected.

``We have payroll data...and the U.S. presidential election next week. Events are still ahead. People will find it difficult to take direction,'' she said, adding that she expected the 10-year yield to trade in a range of 0.750 and 0.790 percent.

A victory by Republican challenger Mitt Romney over President Barack Obama on Nov. 6 could alter market expectations that the Federal Reserve will continue its easy policy through mid-2015, as Republicans have objected to aggressive easing.

``The election could affect the U.S. Treasuries market and have an impact on the JGB trend as well,'' said Ayako Sera, a market economist at Sumitomo Trust and Banking.

The 10-year yield added 1 basis point to 0.770 percent and was on track to add 0.5 basis point on the month. Since Sept. 24, the yield on the benchmark 10-year JGB has fluctuated in a 4 basis-point range between 0.755 percent and 0.795 percent.

Ten-year JGB futures fell 15 ticks to 144.25, holding above their five-day moving average of 144.23.

Yields on 20-year debt rose half a basis point to 1.695 percent, while those on the 30-year bonds edged up half a basis point to 1.955 percent.

So far this month, longer-dated maturities have underperformed, partly due to concerns over political issues and investors positioning at the start of the second half of Japan's financial year ending March 2013.