GRAINS-U.S. corn, wheat at 2-week highs, soy also firm on rain risks

* Wet, cool weather seen delaying Midwest planting

* Rain also poses risk for winter wheat harvest

* New 6-month low for dollar also supports

(Updates with European trading, changes byline/dateline) PARIS/SINGAPORE, May 22 (Reuters) - Chicago corn and wheat extended gains on Monday to notch up two-week highs, while soybeans also stayed firm as wet, cool weather in U.S. grain belts raised risks for spring crop planting and winter wheat harvesting. Persisting weakness in the dollar, which touched a new six-month low against a basket of currencies, also underpinned U.S. futures, although large U.S. and global grain inventories continued to cap prices. The Chicago Board Of Trade most-active corn contract was up 0.3 percent at $3.73-3/4 a bushel by 1156 GMT, after climbing to its highest since May 4 at $3.74-3/4 a bushel. Wheat added 0.7 percent to $4.38-1/4 a bushel, near the session high of $4.39-1/4 a bushel - the highest since May 8. Soybeans were up 0.4 percent at $9.56-1/2 a bushel. "Bad weather is continuing to delay U.S. planting of corn and soybeans," said Kaname Gokon from Tokyo brokerage Okato Shoji. "There is lot of rain and cold weather in the Midwest." Traders will get an indication of crop conditions after the market close on Monday when the U.S. Department of Agriculture issues its weekly crop progress report. Corn in some areas of the Midwest will need reseeding due to flooding and poor crop emergence and may have missed the optimal planting window, while late soybean planting was being slowed by showers. Rainfall has also caused concern about winter wheat in the run-up to harvesting. Forecasts called for unfavorably wet weather in the central Plains hard red wheat zone in the next 2 weeks but more limited rain prospects in the southern Plains could help harvesting, the Commodity Weather Group said in a daily note. The weaker dollar was helping U.S. export prospects, although analysts said last week's sale of U.S. wheat to Egypt may not herald a trend with competition from Black Sea origins set to intensify when 2017 harvest supplies come onto the market. Soybeans were recovering from a slide last week triggered by a plunge in Brazil's real, which saw farmers rush to sell record supplies. Supplies from the large Brazilian soybean harvest are expected to dominate export trade in the coming months, but reluctant selling by farmers has given a longer than expected window for U.S. shipments.

Prices at 1156 GMT

Last Change Pct End Ytd Pct Move 2016 Move CBOT wheat 438.25 3.00 0.69 408.00 7.41 CBOT corn 373.75 1.25 0.34 352.00 6.18 CBOT soy 956.50 3.50 0.37 1004.00 -4.73 Paris MAT wheat Sep 167.25 1.50 0.90 168.00 -0.45 Paris maize Jun 167.00 0.25 0.15 166.00 0.60 Paris rape Aug 361.50 1.00 0.28 408.50 -11.51 WTI crude oil 50.81 0.48 0.95 53.72 -5.42 Euro/dlr 1.12 0.00 0.29

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 David Evans)