PARIS/SINGAPORE- Chicago soybean futures fell 2% on Wednesday to their lowest in more than a week as rains across South America eased supply concerns and encouraged selling after recent multi-year highs.

A further slide for palm oil futures, which hit a two-month low, also weighed on other oilseed markets like soybeans. POI/

Corn shed nearly 2% as the feed grain was also pressured by beneficial rain for South American crops, after a 7-1/2 year high peak last week.

Chicago wheat tracked losses in corn, as a rally to a 6-1/2 year high sparked by a planned Russian export tax subsided.

Grain markets have seen sensitive to South American harvest prospects after brisk Chinese import demand eroded available supply worldwide.

"Soybean prices have rallied on the back of Chinese demand but the market is coming down due to South American weather," said one trader at a Singapore-based company that supplies the oilseed to China.

Rains across much of Brazil's growing regions bolstered parched crops, as the country slowly begins its soybean harvest. 

Much of Brazil and northern Argentina was forecast to see more showers in the week ahead.

The Chicago Board of Trade (CBOT) most-active soybean contract Sv1 was down 2.0% at $13.57-1/1 a bushel by 1226 GMT.

It was on track to fall for a third straight session as it retreated from a 6-1/2 year high above $14 struck last week.

However, tightening U.S. supplies and strong Chinese demand could keep grain prices relatively high. 

"With beans alone, you could see a couple of dollars setback and still have a clear uptrend in play," Mike Lung of U.S. brokerage Allendale said in a market commentary.

The U.S. market is awaiting policy steps by President-elect Joe Biden, who takes office on Wednesday, on issues like biofuel mandates and anti-coronavirus measures that could affect grain demand.

The U.S. Environmental Protection Agency on Tuesday granted three waivers to oil refiners that exempt them from biofuel blending obligations, a last-minute move before President Donald Trump leaves office. 

CBOT corn was down 2.0% at $5.15-1/2 a bushel, and wheat was 2.2% lower at $6.57-3/4.

Commodity funds were net sellers of CBOT corn, soybean, soymeal, wheat and soyoil futures contracts on Tuesday, traders said. 

(Reporting by Gus Trompiz in Paris and Naveen Thukral in Singapore; Editing by Subhranshu Sahu and Pravin Char) ((gus.trompiz@thomsonreuters.com; +33 1 49 49 52 18; Reuters Messaging: gus.trompiz.thomsonreuters.com@reuters.net))