* Soybeans, corn fall as U.S. harvest gathers pace * Wheat down for 3rd week in 4 on ample world supply (Adds details, quotes) By Naveen Thukral SINGAPORE, Sept 16 (Reuters) - Chicago soybeans and corn futures lost ground on Friday with both poised for a decline of more than three percent this week as harvest of all-time high U.S. crops pressure prices. Wheat eased too and was on track to post its third weekly drop in four amid abundant global supplies. Chicago Board of Trade most-active soybeans slid 0.2 percent to $9.49 a bushel by 0324 GMT, while corn lost 0.5 percent to $3.28-1/2 a bushel. Wheat gave up 0.5 percent to $3.97-1/2 a bushel. "Big harvests are progressing and farmer-selling is coming out," said one Sydney-based broker. "Corn and soybeans are being harvested in the United States and we expect agricultural markets to remain under pressure over the coming weeks." For the week, soybeans are down 3.2 percent, corn has lost 3.7 percent and wheat has given up 1.5 percent. Strong demand for soybeans could limit losses. The U.S. Department of Agriculture said that private exporters sold 110,000 tonnes of U.S. soybeans to unknown destinations on Thursday. That marked the government's first daily soybean sales announcement in a week. The USDA reported export sales of U.S. soybeans in the week to Sept. 8 at more than 1 million tonnes, in line with trade expectations. The USDA reported weekly export sales of 2016/17 U.S. corn at 703,500 tonnes, below a range of trade expectations for 800,000 to 1,100,000 tonnes. U.S. soy processors crushed 2.6 percent fewer beans in August than a year ago and the pace fell below market expectations due to declines at plants in the Southwest, the National Oilseed Processors Association (NOPA) said. NOPA said its members crushed 131.822 million bushels of soybeans in August, down from 143.715 million during July. In August 2015, the NOPA crush was 135.304 million bushels. In the wheat market, Egypt, the world's top buyer, last month adopted a zero-tolerance policy on ergot, a grain fungus, in imported wheat, complicating its efforts to source wheat. State grain buyer GASC cancelled its international wheat tender on Aug. 31 after receiving just one offer. Commodity funds were net sellers of CBOT corn and wheat futures contracts on Thursday and net buyers in soybeans, traders said. Trade estimates of net selling in corn ranged from 2,000 to 7,000 contracts, and estimates of net buying in soybeans ranged from 3,000 to 5,000 contracts. Grains prices at 0324 GMT Contract Last Change Pct chg Two-day chg MA 30 RSI CBOT wheat 397.50 -2.00 -0.50% -1.36% 418.96 66 CBOT corn 328.50 -1.50 -0.45% -0.98% 332.58 60 CBOT soy 949.00 -1.50 -0.16% +0.66% 977.38 29 CBOT rice 9.81 $0.02 +0.20% -0.86% $9.80 65 WTI crude 43.66 -$0.25 -0.57% +0.18% $45.39 40 Currencies Euro/dlr $1.124 $0.000 -0.02% -0.09% USD/AUD 0.7519 0.001 +0.07% +0.71% Most active contracts Wheat, corn and soy US cents/bushel. Rice: USD per hundredweight RSI 14, exponential (Reporting by Naveen Thukral; Editing by Himani Sarkar)