U.S. corn sales to China fell 85 percent last week, government data showed on Friday, as the export market was roiled by Beijing’s tighter screening for an unapproved strain of GMO corn. Shippers have been forced to divert cargoes already on the water destined for China, the world’s biggest consumer of feed grain. Uncertainty over the government policy has cast a pall over the entire market, limiting gains in futures and worrying farmers. In the week to Dec. 19, China booked just 19,000 tonnes of corn for delivery during the 2013/14 marketing year, the U.S. Agriculture Department said on Friday. That was the lowest reported total since the week ended Sept. 5., although the USDA did not provide weekly sales totals during the government shutdown in October. The sales were down sharply from 124,000 tonnes in the previous week and accounted for just 10 percent of the average total over the past eight weeks. This week’s slowdown in new deals came after China’s quarantine authority confirmed that it refused 545,000 tonnes of U.S. corn in November and December because shipments contained Syngenta AG’s MIR 162 corn, a GMO variety that has been awaiting China’s approval for more than two years. “It is a problem today,” said Tom Grisafi, president of agricultural advisory service Trade the Farm LLC. “When your biggest customer wants to play games, they can get away with it. Every farmer I talked to today is aware of it.” Cargoes are still leaving the United States, albeit at a slower pace. U.S. exporters shipped 204,600 tonnes of corn to China this week, down 17 percent from a week ago and the smallest amount since early November, the data showed. The cargoes to China accounted for about 15 percent of U.S. corn shipped overseas, the lowest percentage since mid-September. Exports to China will likely continue to fall in the coming weeks, said Tom Fritz, a partner with EFG Group in Chicago, unless a deal on GMO varieties can be reached. USDA has projected that China will import 7 million tonnes of U.S. corn in the 2013/14 marketing year. Beijing also has begun to reject U.S. dried distillers grains (DDGs), a byproduct of corn ethanol production that is used as animal feed. Xinhua News Agency reported on Friday that China’s quality watchdog confirmed the rejection of two U.S. cargoes of DDGs containing traces of MIR 162. Exporters have so far been able to find buyers for the rejected corn. USDA’s report showed that Japan snapped up 41,100 tonnes of corn that was originally headed to an unknown destination, which analysts say is usually China. U.S. corn export sales of 1.479 million tonnes were the highest weekly total since the end of October. But traders fear some buyers are holding out for lower prices as merchants look to offload unwanted cargoes. South Korea’s Nonghyup Feed Inc, the country’s largest animal feed maker, rejected all offers in its tender for 70,000 tonnes of feed corn. “They passed because they know there is a bunch of afloat corn that is looking for a home,” EFG’s Fritz said. “They figure, ‘I can buy it on the cheap.’” Chicago Board of Trade corn futures for March delivery ended up 1-1/4 cents at $4.27-1/2 a bushel. Corn prices fell 1.3 percent this week, their biggest weekly loss in a month.