GRAINS-Wheat curbed by global supply as market waits on USDA report

* Grain markets consolidate before Sept. 12 USDA forecasts

* Big Russian crop, new Egypt import snag weigh on wheat

* Focus of USDA report to be corn, soybean yield revisions

(Updates with European trading, changes byline/dateline) PARIS/SINGAPORE, Sept 11 (Reuters) - Chicago wheat eased on Monday as swelling harvest supplies in the Black Sea export region hung over a subdued market a day ahead of closely watched U.S. government crop forecasts. Corn futures also slipped while soybeans were marginally higher as investors adjusted positions before Tuesday's U.S. Department of Agriculture (USDA) crop report that will be watched in particular for revised estimates of U.S. corn and soybean yields. The Chicago Board of Trade most-active wheat contract was 0.9 percent lower at $4.34 a bushel by 1129 GMT, reversing a small rise seen during Asian trading. Despite a drop in U.S. wheat production this year, a record Russian harvest and large crop in Ukraine are expected to keep international markets well supplied this year. "There seems to be no end to the upward revisions of the 2017/18 Russian crop," Commerzbank analysts said in a note. "Russia has been able to step up its exports by 7 percent so far this season." Renewed uncertainty over import conditions in Egypt also dampened sentiment. The world's biggest wheat importer is considering rejecting a French wheat cargo due to the presence of poppy seeds, raising the threat of a fresh standoff with suppliers over inspection terms. In Canada, meanwhile, the spring wheat harvest could be larger than expected, adding to ample global supplies of the grain, crop analysts said, although quality has been variable. The most-active CBOT corn contract was down 0.4 percent at $3.55-1/4 a bushel while soybeans were up 0.2 percent at $9.64-1/4 a bushel. Analysts broadly expect the USDA to trim its U.S. corn yield forecast in Tuesday's monthly report but good yields are still anticipated, which could maintain large stockpiles. There has been some concern over soybean yields after dry conditions in part of the U.S. Midwest and the risk of some damage from Hurricane Irma to soy crops in the southeast. Soybean prices have also drawn support from export demand, which has countered supply pressure from a record Brazilian crop. The USDA said on Friday morning that private exporters reported the sale of 264,000 tonnes of soybeans to China for delivery during the 2017/18 marketing year, the biggest flash sale in 2-1/2 weeks. Weekly export sales of soybeans totalled 1.16 million tonnes, the USDA said, topping market forecasts. China, the world's largest soybean buyer, imported 8.45 million tonnes of soybeans in August, a record for the month, customs figures showed.

Prices at 1129 GMT

Last Change Pct End Ytd Pct Move 2016 Move CBOT wheat 434.00 -3.75 -0.86 408.00 6.37 CBOT corn 355.25 -1.50 -0.42 352.00 0.92 CBOT soy 964.25 2.25 0.23 1004.00 -3.96 Paris wheat Dec 159.75 0.25 0.16 175.00 -8.71 Paris maize Nov 158.00 -0.50 -0.32 170.00 -7.06 Paris rape Nov 361.50 -2.00 -0.55 383.25 -5.68 WTI crude oil 47.76 0.28 0.59 53.72 -11.09 Euro/dlr 1.20 0.00 -0.21

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

(Reporting by Naveen Thukral and Gus Trompiz in Paris; Editing by Joseph Radford and Louise Heavens)