SINGAPORE, Jan 13 (Reuters) - Chicago corn jumped 4% on Wednesday to a 7-1/2-year high and soybeans climbed to their loftiest since June 2014 after a widely watched U.S. report reduced its forecast for global supplies.

Wheat rose for a second straight session.

FUNDAMENTALS

* The most-active corn contract on the Chicago Board of Trade (CBOT) was up 3% at $5.32 a bushel, as of 0136 GMT, after climbing to its highest since mid-2013 at $5.39 a bushel.

* Soybeans were up 0.8% at $14.29-3/4 a bushel, after climbing to their highest since June 2016 at $14.37 a bushel, and wheat rose 1.1% to $6.72 a bushel.

* U.S. soybean and corn supplies in September will be smaller than previously forecast due to a reduced estimate of last fall's harvest, the U.S. Department of Agriculture (USDA) said on Tuesday.

* The crop revisions will intensify fears of shortages in 2021, after governments tried to lock in extra food supplies amid the COVID-19 pandemic that disrupted global supply chains and thinned U.S. stockpiles.

* The agency pegged the 2020 U.S. corn harvest at 14.182 billion bushels based on an average yield of 172.0 bushels per acre and soybean production at 4.135 billion bushels on a yield of 50.2 bushels. All were below average trade expectations, particularly in the case of corn.

* The USDA also forecast end-of-season corn and wheat supplies below trade estimates, and confirmed investor fears of the tightest U.S. soybean stocks in seven years.

* It also lowered its forecasts for upcoming harvests in key export countries Brazil and Argentina.

* Argentina said on Tuesday it lifted a 30,000-tonne-per-day limit recently placed on corn exports, which had caused farmers to go on a sales strike in protest.

* Growers have withheld crops from market since early Monday, angered by what they said was overzealous intervention in the markets. The government said the curb was intended to ensure ample domestic food supplies and stable prices.

MARKET NEWS

* Asian stocks opened mostly higher on Wednesday, tracking modest Wall Street gains as prospects of an eventual victory against coronavirus shored up recovery hopes, while tight supply expectations pushed oil prices to their highest in a year.

DATA/EVENTS (GMT) 0900 ECB President Christine Lagarde speaks at Reuters Next summit 1330 US CPI MM, SA Dec 1900 US Federal Reserve issues the Beige Book (Reporting by Naveen Thukral; Editing by Subhranshu Sahu)