GRAINS-Wheat extends retreat as focus stays on high supply, slow exports

* Wheat down for third day, touches 1-week low

* Small export sales, high stocks offset weather worries

* Soybeans at 1-month high, buoyed by brisk exports

(Updates with European trading, changes byline/dateline) PARIS/SYDNEY, April 13 (Reuters) - Chicago wheat futures fell for a third straight session on Friday to touch a one-week low as tepid U.S. exports and high global supplies outweighed recent concern about adverse weather in U.S. wheat belts. Soybeans rose to reach a one-month high as brisk export demand continued to support the oilseed market and counter lingering concerns about trade tensions between the United States and top soybean importer China. Corn was little changed. "U.S. export sales continue to be dismal given it has not been competitive outside its own backyard for quite some time," said Tobin Gorey, director of agricultural strategy at the Commonwealth Bank of Australia. The U.S. Department of Agriculture (USDA) reported export sales for old and new crop U.S. wheat in the latest week at 188,700 tonnes, below trade expectations. This came after the USDA on Tuesday raised its forecast of U.S. 2017/18 wheat ending stocks by more than expected, and increased its outlook for world wheat stocks to a new all-time high. Weather forecasts projecting heavier rain in the parched U.S. Plains next weekend also pressured prices, easing concern about crop conditions that had driven Chicago futures to a near one-month high earlier this week. Analysts said, however, that weather conditions would have to be monitored given persistent drought in the U.S. Plains and cold weather that could hold up spring planting. "Despite awaited rainfall, operators will remain cautious in view of low temperatures which could once again raise concerns about damage to wheat and delay corn plantings," consultancy Agritel said in a note. "For the next 15 days, it will be necessary to monitor sowing conditions in the Corn Belt and a possible switch from corn to soybean, if delays in spring planting are confirmed." The most active wheat futures on the Chicago Board Of Trade were down 1.5 percent at $4.73-3/4 a bushel by 1032 GMT, just off an earlier one-week low of $4.72-3/4. The most active CBOT soybean contract rose 0.4 percent to $10.64-3/4 a bushel. It earlier reached $10.67-1/4, its highest since March 8. CBOT corn inched down 0.1 percent to $3.88-1/4 a bushel. The USDA reported export sales of old and new crop U.S. soybeans in the week to April 5 at 2,464,500 tonnes, topping a range of trade expectations. Sales of old-crop soybeans topped 1.5 million tonnes, the most in five weeks.

Prices at 1032 GMT

Last Change Pct End Ytd Pct Move 2017 Move CBOT wheat 473.75 -7.25 -1.51 427.00 10.95 CBOT corn 388.25 -0.50 -0.13 350.75 10.69 CBOT soy 1064.75 4.00 0.38 961.75 10.71 Paris wheat May 164.75 -0.75 -0.45 162.50 1.38 Paris maize Jun 165.75 -0.50 -0.30 163.50 1.38 Paris rape May 348.00 0.00 0.00 352.75 -1.35 WTI crude oil 67.39 0.32 0.48 60.42 11.54 Euro/dlr 1.23 0.00 0.10

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

(Reporting by Gus Trompiz in Paris and Colin Packham in Sydney; Editing by Tom Hogue and David Evans)