* Buy-stops, options call buying lift soy
* Exports, US freeze buoy wheat, Paris futures at 7-mth high
* Bigger-than-expected Canadian crop curbs wheat rally
(Updates to include U.S. trading session, adds fresh analyst quotes, details change in soy market sentiment, changes dateline from PARIS/SYDNEY)
CHICAGO, Dec 4 (Reuters) - U.S. soybean futures climbed 1 percent on Wednesday reversing two days of declines on technical buying and despite prospects for a huge soy output in South America.
"I don't see any thing fundamentally to do this, it was technical with buy-stops hit and there also was buying of March $13.20 calls in options, which helped," a trader said.
U.S. and European wheat futures turned choppy, with Paris prices setting a near seven-month high, as a clutch of international tenders kept the market focused on brisk export demand and as cold weather posed a threat to some U.S. winter wheat areas.
But a much bigger-than-expected official estimate of the wheat harvest in Canada turned the U.S. wheat market lower and curbed the rise in European wheat values.
Corn rose to a two-week high on technical short-covering and despite confirmation that China rejected some U.S. corn cargoes.
At 9:55 a.m. CST (1555 GMT), Chicago Board of Trade January soybeans were up 9-1/2 cents per bushel at $13.29-1/4, December wheat was down 2-1/2 at $6.51-1/4.
Some traders were becoming more optimistic about export prospects for European and U.S. wheat stocks.
The United States and the European Union are seen as among the best placed in the short term to supply wheat to major importing countries in north Africa and the Middle East, with export competition from Russia and Ukraine fading.
Egypt, the world's top wheat importer, held its fifth international tender in as many weeks on Tuesday, while Algeria and Tunisia also launched tenders this week, in a sign that rising wheat prices have not curbed demand for the food staple.
Forecasts for freezing weather this week in the U.S. wheat belt also supported prices by raising the risk of damage to developing crops.
"Russian wheat export prices strengthened despite being bypassed by Egypt, so U.S. wheat is even more competitive," said Vanessa Tan, investment analyst at Phillip Futures in Singapore.
"There are also forecasts that the U.S. will experience very cold conditions, which could put up to 5 percent of the winter wheat crop at risk."
Bitter cold temperatures and blowing snow were expected in the U.S. Plains beginning late Wednesday and into the weekend, posing a threat to wheat and livestock, an agricultural meteorologist said.
Wednesday's crop estimate from Statistics Canada, which put 2013 all-wheat production at a record 37.53 million tonnes, against an average trade forecast of 33.8 million, cooled prices by turning attention back to higher global supply this year.
In Europe, March milling wheat on the Paris-based Euronext market was up 0.36 percent at 209.75 euros a tonne. It earlier reached 211.25 euros, a level last seen on the contract on May 9 as it tested chart resistance at 211 euros.
Egypt bought 60,000 tonnes of Romanian wheat on Tuesday for shipment between Dec. 20 and Dec. 31, the main government wheat buying entity said.
Although Egypt's GASC turned down offers of French wheat, a tender being held by Algeria, the top destination for France's wheat exports, maintained a bullish mood on the French market.
"The volumes available for export are shrinking in the Black Sea area. In 2014, American and French origins will be on the front of the stage," French consultancy Agritel said.
CBOT December corn was up 4-1/2 cents per bushel at $4.26-1/4 a bushel.
Front-month prices on Monday sank to a new three-year low of $4.10, as talk that China had rejected more U.S. corn due to an unauthorised genetically modified variety added to supply pressure from an expected record-large U.S. harvest.
Subsequent confirmation on Wednesday that China rejected the entry of five batches of U.S. corn did not have a significant impact on prices, although analysts said the move could be the sign of a tougher Chinese line on imports.
(Additional reporting by Gus Trompiz in Paris and Colin Packham in Sydney; Editing by Marguerita Choy)