GRAINS-Soybeans rise on harvest concerns; corn firm; wheat weak

(Updates with U.S. trading, adds analyst quote, changes byline, dateline, previous PARIS/SINGAPORE)

CHICAGO, Oct 5 (Reuters) - U.S. soybean futures rose 1.2 percent on Thursday to their highest in nearly a week, supported by reports of some disappointing yields in key Midwest production areas and technical buying, traders said.

Concerns about rains slowing down the U.S. harvest, which was already behind the typical pace, added further strength to soybeans. The weather outlook also underpinned corn, but gains were kept in check by weakness in the wheat market.

"You have got some rain so we are probably going to be limited on harvest pressure in the short term," said Mark Schultz, chief analyst at Northstar Commodity Investment Co.

Wheat futures were trading in negative territory after failing to break through technical resistance early in the session.

At 10:18 a.m. CDT (1518 GMT), Chicago Board of Trade November soybean futures were up 11-1/4 cents at $9.69-1/2 a bushel. Soybeans hit their highest since Sept. 29 earlier in the session.

"The U.S. soybean harvest is being delayed as rains seem to be an issue," said Phin Ziebell, agribusiness economist at National Australia Bank.

Soybeans firmed overnight trading but gains accelerated during the daytime session after the November contract broke through its 10-day and 20-day moving averages.

CBOT December corn was up 1/2 cent at $3.48-3/4 a bushel.

The U.S. Agriculture Department said weekly export sales of corn totalled 814,100 tonnes, topping market forecasts that ranged from 500,000 to 700,000 tonnes. Export sales of soybeans and wheat were in line with trade estimates.

CBOT December soft red winter wheat was down 1-3/4 cents at $4.40-1/4 a bushel, hitting their lowest since Sept. 19.

Wheat prices remained capped by export competition created by a record Russian harvest this year. Analysts said that U.S. offerings were still too expensive for overseas buyers despite the recent futures weakness. (Additional reporting by Naveen Thukral in Singapore and Gus Trompiz in Paris; Editing by David Goodman and James Dalgleish)