GRAINS-Wheat slips again on ample world supply; corn, soy resume slide

* CBOT wheat near 1-month lows, Euronext sees contract lows

* Big-looking Russian harvest tempers U.S. crop woes

* Corn, soy give up day-earlier gains, mild weather weighs

(Updates with European trading, changes byline/dateline) PARIS/SINGAPORE, Aug 3 (Reuters) - Chicago wheat futures extended losses for a fourth consecutive session on Thursday to trade near a one-month low as the prospect of a bumper Russian harvest underscored ample global supplies despite an expected sharp fall in U.S. output. Corn and soybean prices also eased, hitting new one-month lows after a day-earlier rebound petered out, with mild weather forecasts for the Midwest crop belt reducing concerns about yield losses. The Chicago Board of Trade most-active wheat contract lost 0.9 percent to $4.56-1/2 a bushel by 1121 GMT, holding just above Wednesday's low of $4.55-3/4, the weakest since late June. In Europe, the most active December wheat futures on Euronext fell to a contract low of 168.50 euros a tonne, with a day-earlier 2-1/2 year high for the euro against the dollar also weighing. Talk of a record Russian crop has tempered concern about poor conditions for U.S. spring wheat, which fueled an early summer rally on wheat markets. "The Russian production has been revised up ... and is offsetting for now the dry conditions in the U.S., Canada and Australia," consultancy Agritel said in a note. Russian agriculture consultancy IKAR on Tuesday increased its estimate for this year's wheat harvest in Russia to a record 74-77 million tonne range.

Together with a better than expected French harvest, the bumper Russian crop should keep export markets well supplied. However, analysts said wheat markets could find fresh support if the U.S. spring wheat harvest now under way shows yields are even worse than anticipated, while concerns over wet weather in Germany and lack of rain in Canada and Australia may also resurface in the coming weeks. "We see the downside limited for wheat because dryness in U.S., Canada and Australia is curbing global supplies," one agricultural commodities analyst said. CBOT corn gave up 1.0 percent to $3.75-1/4 a bushel, its lowest since June 30. Soybeans were down 1.8 percent at $9.59-3/4 a bushel, after setting a new low since June 30 at $9.58-3/4. For corn and soybeans, weather forecasts showed few serious threats in the next two weeks for the heart of the U.S. Midwest crop belt. The corn crop is filling kernels and soybeans are in the pod-setting phase. Corn rose on Wednesday, helped by commodity brokerage INTL FCStone's harvest forecast that was below the USDA's most recent forecast. Attention is now shifting to the USDA's next monthly forecasts on Aug. 10 to see if it cuts yield outlook. Grain markets will get an update on export demand on Thursday from weekly USDA export sales data due at 1230 GMT.

Prices at 1121 GMT

Last Change Pct End Ytd Pct Move 2016 Move CBOT wheat 456.50 -4.25 -0.92 408.00 11.89 CBOT corn 375.25 -3.75 -0.99 352.00 6.61 CBOT soy 959.75 -17.75 -1.82 1004.00 -4.41 Paris wheat Dec 168.50 -1.25 -0.74 175.00 -3.71 Paris maize Nov 164.50 -0.50 -0.30 170.00 -3.24 Paris rape Nov 364.00 -4.00 -1.09 383.25 -5.02 WTI crude oil 49.60 0.01 0.02 53.72 -7.67 Euro/dlr 1.18 0.00 -0.13

Most active contracts - Wheat, corn and soy US cents/bushel, Paris futures in euros per tonne

(Reporting by Naveen Thukral in Singapore and Gus Trompiz in Paris; Editing by Tom Hogue and Susan Thomas)