(Adds details on largest cancellation in 14 months, adds quote, background)
Jan 3 (Reuters) - Chinese importers canceled their largest U.S. corn purchases in 14 months last week, U.S. government data showed on Friday, while several more cargoes of the grain initially bound for China were diverted to other Asian nations.
China has rejected numerous cargoes of U.S. corn since mid-November because they contained Syngenta AG's MIR 162 corn, a genetically modified variety not approved for import by China.
A U.S. trade delegation visiting China last month failed to reach an agreement on the GMO corn strain, which is approved for import by all other major world corn buyers.
"It's more of what we've all been expecting, given the situation with MIR 162 in China," said Dan Basse, president of AgResource Co, an industry consultant.
"Some cargoes are making it in, and some are not making it in. We need to expect all of this will persist until probably late in the first quarter or some time in the second quarter."
The U.S. Department of Agriculture reported a net cancellation of 116,000 tonnes in corn sales to China in the week ended Dec. 26, the most in a single week since October 2012.
The USDA's weekly report also showed a net decrease of 209,400 tonnes in sales to "unknown destinations," 101,400 tonnes of which were earmarked for Japan.
Since exporters are only obligated to report the grain's destination when it is loading, sales are sometimes reported to "unknown destinations" to disguise the buyer, traders said. Sales to China are often initially reported under that category.
The USDA also reported a nearly 200,000-tonne decrease in accumulated exports to China for the weeks ended Nov. 28 and Dec. 5. That corn was resold to South Korea, confirming private reports that cargoes rejected by China have been resold to its neighbor.
Despite the rejections, U.S. exporters continued to load corn vessels to China. About 154,900 tonnes were exported last week, down from 204,500 tonnes in the previous week, the USDA data showed.
The USDA has forecast China's corn imports in the 2013/14 (Sept/Aug) season at 7 million tonnes, but the lack of a resolution on MIR 162 suggested imports could be considerably smaller. The United States supplies nearly all of China's imported corn.
About 600,000 tonnes of U.S. corn are on vessels currently sailing to China and another 2.15 million tonnes are sold but not yet shipped, according to trade sources and USDA data. (Reporting by Karl Plume in Chicago; Editing by Meredith Mazzilli and Jeffrey Benkoe)