SINGAPORE  - Chicago corn and soybean futures slid around 1% on Tuesday, weighed down by a broad commodity sell-off on concerns over rising COVID-19 cases in key consumption centres.

Wheat lost ground, giving up some of the last session's strong gains although expectations of lower output in top exporters Russia and the United States limited decline.

"Grains and oilseed prices had rallied on the back of production concerns but now we have to see if these high prices are sustainable or not," said Phin Ziebell, an agribusiness economist at National Australia Bank in Melbourne.

"People are eating out less as COVID-19 cases are rising again. China is a big feed grain consumer and it is witnessing an increase in cases."

The most-active corn contract on the Chicago Board of Trade (CBOT) slid 0.9% to $5.54-1/2 a bushel by 0302 GMT, having gained 2.6% in the previous session.

Soybeans were down 1.1% at $13.39-1/4 a bushel and wheat lost 0.9% to $7.23 a bushel.

Asian stocks slipped as the Delta coronavirus variant spread in key markets in the region and put Chinese authorities on high alert, rattling investor confidence. 

However, concerns over grain and oilseed output are likely to curb losses.

The U.S. Department of Agriculture rated 62% of the U.S. corn crop in good-to-excellent condition in its weekly crop progress report on Monday, down 2 percentage points from the previous week, a larger decline than most analysts had expected. 

Ratings for soybeans improved, bucking trade expectations for a slight drop. The USDA rated 60% of the oilseed crop as good to excellent, up from 58% a week ago, while analysts on average had expected a 1-point decline.

Russian agriculture consultancy Sovecon said on Monday it had cut its forecast for Russia's 2021 wheat crop by 5.9 million tonnes to 76.4 million tonnes. 

An annual U.S. crop tour last week projected the average spring wheat yield in North Dakota at 29.1 bushels per acre this year, its lowest since 1993.

Unfavourable weather caused second corn yields in the center-south of Brazil to plunge to their lowest level in 10 years, agribusiness consultancy AgRural said on Monday, projecting productivity at 66.6 60-kilo bags per hectare. 

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

(Reporting by Naveen Thukral; editing by Uttaresh.V) ((naveen.thukral@thomsonreuters.com; +65-6870-3829; Reuters Messaging: naveen.thukral.thomsonreuters.com@reuters.net))