* U.S. corn, soybean ratings improve, topping trade expectations
* Wheat prices extend recent fall with supplies seen ample
LONDON, Aug 15 (Reuters) - Chicago corn and soybean futures fell on Tuesday after a weekly report from the U.S. government showed better-than-expected conditions for both crops.
Wheat fell for a third consecutive session.
The most-active soybean contract on the Chicago Board of Trade (CBOT) lost 0.5% to $13.19-1/2 a bushel, as of 1102 GMT, and corn fell 0.9% to $4.83-1/4 a bushel.
Wheat was down 1.1% at $6.09-1/4 a bushel.
Weekly condition ratings for the U.S. soybean and corn crops improved in the past week more than analysts expected, U.S. government data showed on Monday.
The U.S. Department of Agriculture's (USDA) weekly crop progress report rated 59% of the corn crop as good to excellent, up from 57% a week ago, while 11 analysts surveyed by Reuters on average had expected an improvement of 1 percentage point.
The USDA also rated 59% of the soybean crop as good to excellent, a jump from 54% last week.
Beneficial rains in recent weeks have eased drought conditions in position of the Midwest crop belt.
"The U.S. is expected to have favourable weather for a fourth week in a row in corn and soybean areas," commodities broker Czarnikow said in a note, adding tight old crop supplies may limit the scope for further losses.
Brazilian farmers had harvested 71% of the area planted for their second corn crop in the centre-south region by Aug. 10, consultancy AgRural said on Monday, up 7 percentage points from the previous week.
Dealers said wheat supplies remained ample, despite the continued disruption of the flow from Ukraine, partly due to the strong pace of exports from Russia. (Additional reporting by Naveen Thukral in Singapore; Editing by Subhranshu Sahu, Eileen Soreng and Shounak Dasgupta)
