GRAINS-Wheat falls further, corn and soy slip on supply pressures

* Wheat falls for 3rd session, hits lowest since mid-June

* USDA estimates, big Russian crop dent price sentiment

* MGEX, Euronext wheat futures also extend slide

* Corn, soybean at new 6-week lows on U.S. crop outlook

(Updates with European trading, changes byline/dateline) PARIS/SINGAPORE, Aug 14 (Reuters) - Chicago wheat futures dropped on Monday for a third session, weakened by big harvests in the Black Sea region and a smaller than expected cut in the U.S. government's spring wheat forecast. Corn and soybeans slipped to new six-week lows, as a moderate weather outlook and higher-than-anticipated yield projections from the U.S. Department of Agriculture (USDA) last week kept prices under pressure. The Chicago Board of Trade's most-active wheat contract lost 1.5 percent to $4.32-3/4 a bushel by 1142 GMT, after declining earlier in the session to $4.31-1/2, the lowest since June 12. Other wheat futures markets also slipped, led by Minneapolis spring wheat which shed over 2 percent. This added to a 4 percent plunge on Friday after the USDA in its Aug. 10 report lowered the spring wheat crop outlook by less than analysts had expected. Kansas hard red winter wheat futures also fell, while in Europe milling wheat futures on Euronext set new contract lows. "Chicago and Kansas both managed to almost complete the journey back to the bottom of their range for the past year," said Tobin Gorey, director of agricultural strategy at Commonwealth Bank of Australia in Sydney, referring to the wheat markets in Chicago and Kansas City. The USDA's supply outlook last Thursday included a sharp increase in projected global wheat stocks in 2017/18, supported

"As compared with the initial (USDA) estimate back in May, the Russian crop is now expected to be over 10 million tonnes higher," Commerzbank analysts said in a market note. Leading Russian agriculture consultancies SovEcon and IKAR also raised their estimates of Russia's 2017 wheat crop sharply to record highs on Friday. Russian wheat export prices fell for the second consecutive week due to the imminent arrival of the massive crop, analysts said on Monday, underlining ample international supplies.

Corn gave up 1.3 percent to $3.70 a bushel, its weakest since June 30. Soybeans dropped 1 percent to $9.35-1/2 a bushel, after also hitting their lowest since June 30 at $9.34-1/2. Corn and soybean prices had steadied on Friday in a pause from heavy selling that followed the USDA's report. But a crop-friendly weather outlook, with moderate temperatures and some rain forecast in the coming week in the Midwest, weighed on sentiment, despite widespread expectations the USDA will reduce its corn and soybean forecasts going forward due to dry conditions this summer. Grain markets will get another indication of harvest prospects from the USDA's weekly crop progress report due after the market close on Monday.

Prices at 1142 GMT

Last Change Pct End Ytd Pct Move 2016 Move CBOT wheat 432.75 -6.50 -1.48 408.00 6.07 CBOT corn 370.00 -4.75 -1.27 352.00 5.11 CBOT soy 935.25 -9.75 -1.03 1004.00 -6.85 Paris wheat Dec 163.25 -2.25 -1.36 175.00 -6.71 Paris maize Nov 162.25 -1.25 -0.76 170.00 -4.56 Paris rape Nov 369.50 -2.25 -0.61 383.25 -3.59 WTI crude oil 48.56 -0.26 -0.53 53.72 -9.61 Euro/dlr 1.18 0.00 -0.19

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 Christian Schmollinger and Susan Fenton)