GRAINS-Prices subdued ahead of USDA crop reports

* Market awaits grain stocks, wheat output data at 1600 GMT

* Traders assess global harvest, planting weather

* Wheat up this month but facing quarterly fall

(Updates with European trading, changes byline/dateline) PARIS/SINGAPORE, Sept 29 (Reuters) - Chicago wheat, corn and soybean futures were little changed on Friday as investors assessed shifting weather conditions in major exporting countries while awaiting U.S. government crop data later in the day. Grain markets are bracing for the U.S. Department of Agriculture's (USDA) estimates of quarterly grain stocks and 2017 wheat production in the United States, due at 1600 GMT. The data will give a key indication for investors trying to work out supply-and-demand trends for the new season. A backdrop of large global inventories has weighed on the market, but weather uncertainty around planting and harvesting of upcoming crops has lent support to prices this month. The Chicago Board of Trade most-active wheat contract was down 0.2 percent at $4.54-1/4 a bushel. It is up about 4.5 percent this month, supported down nearly 14 percent over the third quarter. Analysts surveyed by Reuters on average expect the USDA to lower its estimate of U.S. 2017 wheat production, which could turn attention back to reduced supply of high-protein spring wheat. Forecasters have also been lowering expectations for wheat production in Australia and Argentina after adverse weather. However, other estimates this week have underscored abundant supply of wheat and other grains. The International Grains Council (IGC) raised its forecast for world grain production in 2017/18, with the crop now expected to be the second-largest in history, while Russia's agriculture minister said the country's grain output would reach a record high. "At the top level, the wheat balance sheet is not problematic. The thing to watch is when you break it down to class and quality. There is ongoing reduction in high-protein wheat," said Brett Cooper, Asia head of agricultural commodities at brokerage INTL FCStone. CBOT soybeans were down 0.3 percent at $9.57 a bushel but were up about 1 percent so far over the month. Soybeans have been supported by a run of export sales to China, although the start of the U.S. harvest and worries over biodiesel demand for soyoil have curbed the rally this week. "Operators are remaining cautious on the soybean market in a context of uncertainty regarding the energy policy in the U.S. on biodiesel," consultancy Agritel said in a note. CBOT corn was unchanged on the day at $3.52-1/2 and down 1.5 percent this month. Analysts on average expect the USDA to report U.S. Sept. 1 corn stocks at 2.353 billion bushels, which would be the largest since 1988.

Prices at 1227 GMT

Last Change Pct End Ytd Pct Move 2016 Move CBOT wheat 454.25 -0.75 -0.16 408.00 11.34 CBOT corn 352.50 0.00 0.00 352.00 0.14 CBOT soy 957.00 -2.50 -0.26 1004.00 -4.68 Paris wheat Dec 166.25 -0.25 -0.15 175.00 -5.00 Paris maize Nov 155.25 -0.50 -0.32 170.00 -8.68 Paris rape Nov 368.00 -0.50 -0.14 383.25 -3.98 WTI crude oil 51.63 0.07 0.14 53.72 -3.89 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 Subhranshu Sahu and Mark Potter)