SINGAPORE, June 16 (Reuters) - Chicago soybeans and corn slid on Tuesday, giving up the previous session's gains, as improved U.S. crop ratings amid favourable Midwest weather weighed on prices.

Wheat fell after closing marginally higher on Monday.

FUNDAMENTALS

* The most-active soybean contract on the Chicago Board of Trade (CBOT) (Sv1) fell 0.2% to $11.17-1/4 a bushel by 0010 GMT, corn Cv1 lost 0.4% to $4.13-3/4 a bushel and wheat Wv1 gave up 0.3% to $5.88 a bushel.

* The U.S. Department of Agriculture rated 68% of the nation's corn and 66% of soybeans in good-to-excellent condition, each up 1 percentage point from a week earlier. Spring wheat was rated 55% good-to-excellent, up 3 percentage points from last week.

* Ratings for the winter wheat crop improved but remained near historical lows, reflecting drought in the Southern Plains. The winter wheat harvest was 25% complete, ahead of the five-year average of 13%.

* All three grain markets have been under pressure for most of June as crops in the U.S. Corn Belt have gotten off to a good start.

* The National Oilseed Processors Association (NOPA) said its members crushed 208.785 million bushels of soybeans in May, down 1.4% from April and below nearly all trade estimates. Soyoil stocks held by NOPA members hit a five-month low at 1.735 billion pounds, below all trade estimates.

MARKET NEWS

* Major stock indexes and bond prices rallied while oil futures settled at a three-month low on Monday as U.S. President Donald Trump said a preliminary agreement to end the war in the Gulf has already been signed by the U.S. and Iran. MKTS/GLOB

DATA/EVENTS (GMT)

0200 China Urban Investment (YTD)YY May

0200 China Retail Sales YY May

0200 China Unemp Rate Urban Area May

0900 Germany ZEW Economic Sentiment, Current Conditions Jun

1230 US Housing Starts Number May

1230 US Import Prices YY May

: : Japan JP BOJ Rate Decision June 16