JGBs dip ahead of BOJ's August debt-purchase plan

TOKYO, July 31 (Reuters) - Japanese government bond prices dipped on Monday as some nervousness prevailed ahead of the Bank of Japan's debt-buying operation plan for August.

The benchmark 10-year yield rose half a basis point to 0.075 percent and the 20-year yield climbed 1 basis point to 0.590 percent.

The BOJ will disclose the details of its buying operations in each zone for next month at 17:00 JST (0800 GMT).

After the central bank kept its buying amount unchanged for July focus is on whether it will trim its purchases of mid-to-long-term maturity JGBs.

The BOJ could trim its JGB buying as pressure from other key bond markets is seen to have subsided, with a surge in euro zone and Treasury yields early in the month having run its course.

In the short-end of the curve, three-month euroyen futures, a benchmark of futures trading on short-term interest rates, fell to 99.935, lowest since early April.

The drop was due to three-month euroyen Tokyo interbank offered rate (Tibor) nudging up to 0.0750 percent from 0.0560 percent.

Interbank rates are interest that banks charge each other when they lend money between themselves.

Tibor's rise came after a new method was introduced last week to calculate the rates as part of market reform. (Reporting by the Tokyo markets team)