GRAINS-Soy at 3 week-low on Latam supply, new contract lows for wheat

* Chicago soybeans fall for fourth straight session

* Argentine rain, Brazil crop estimate pressure prices

* Wheat sees new contract lows as global supply weighs

* Corn edges down, market awaits monthly USDA report

(Updates with European trading, changes byline/dateline) PARIS/SYDNEY, Dec 11 (Reuters) - U.S. soybean futures fell for a fourth straight session on Monday to hit a three-week low as beneficial rain in Argentina and rising forecasts for Brazilian output kept attention on high global supply of the oilseed. Wheat eased for a sixth straight session to set fresh contract lows as ample global inventories continued to weigh on prices. Corn ticked lower, with investors also awaiting further direction from monthly U.S. government crop estimates on Tuesday. The most active soybean futures on the Chicago Board Of Trade were down 0.7 percent at $9.82-3/4 a bushel by 1132 GMT. They earlier slipped to $9.82-1/2, their lowest since Nov. 17. Worries about dryness in Argentina, which helped push prices to a four-month high last week, have eased as weather forecasts raise the prospect of rain relief. "Weather forecasters are looking more favorably for a rain event for these regions in mid-December," said Tobin Gorey, director of agricultural strategy, Commonwealth Bank of Australia. In Brazil, consultancy AgRural on Friday raised its forecast for Brazil's 2017/18 soybean harvest to 112.9 million tonnes from 110.2 million. "Estimates of Brazilian soybean production in 2017/18 are doing just what they did last season: rising," Commerzbank analysts said in a note. "That said, sowing is only just coming to an end, so forecasts are still very vague," they added. Grain markets will be watching for any revisions to 2017/18 South American soybean and corn production in the U.S. Department of Agriculture's (USDA) world crop outlook on Tuesday. The most active corn futures fell 0.5 percent to $3.51 a bushel. For wheat, March futures dropped 1.1 percent to $4.14-1/4 a bushel. It earlier set a contract low of $4.14, which also marked the weakest price for a most active wheat contract since the end of January. Wheat is under pressure amid bumper global production, with a higher than expected official estimate of Canadian output last week adding to the bearish supply mood and offsetting doubts over a weather-hit Australian harvest.

Prices at 1132 GMT

Last Change Pct End 2016 Ytd Pct Move Move CBOT wheat 414.25 -4.75 -1.13 408.00 1.53 CBOT corn 351.00 -1.75 -0.50 352.00 -0.28 CBOT soy 982.75 -7.00 -0.71 1004.00 -2.12 Paris wheat Dec 155.00 -1.00 -0.64 175.00 -11.43 Paris maize Jan 153.75 -0.25 -0.16 171.00 -10.09 Paris rape Feb 362.00 -2.75 -0.75 393.00 -7.89 WTI crude oil 57.19 -0.17 -0.30 53.72 6.46 Euro/dlr 1.18 0.00 0.24

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

(Reporting by Colin Packham; Editing by Gareth Jones)