The country, which imports around 2.5 million metric tons (2.75 million tons) of U.S. wheat a year, had been expected to announce final test results today. The delay could drag out a suspension of imports by Korean millers, stoking further market uncertainty after a rogue strain of the crop was discovered in Oregon.
South Korea's food ministry said it would continue its tests later this week after receiving a new GM wheat test system and samples from the United States. Officials declined to say how long this could take.
"This is not at an end to testing. We will continue with tests to be thorough in preventing unapproved wheat from entering the Korean market," Park Hye-kyung, director general of Food Nutrition and Dietary Safety Bureau at the food ministry said in a briefing.
Korean millers last week suspended wheat imports from the U.S. pending tests, after news that unapproved GM wheat had been found growing in Oregon spooked buyers globally.
An official from the Korean Flour Mills Industry Association said on Wednesday that members would discuss the latest results, which come in the wake of government comment on Monday that initial tests on Oregon wheat were negative.
The discovery of the long-forgotten strain of wheat, developed by biotech giant Monsanto (MON.N) more than a decade ago but never put into commercial production, has prompted Japan to shun wheat from the Pacific Northwest.
Some other Asian countries have ramped up inspections and the European Union said it would step up testing.
China's state stockpiler Sinograin has not commented on the GMO scare, but some flour mills have said they were investigating. The country had bought about 1.5 million metric tons of U.S. wheat over the past two months, industry sources said.
MORE CONFIDENT
But some market participants said they would focus on the negative test result rather than the delay in final testing.
"Despite being only initial findings, the results are encouraging," said Andrew Woodhouse, grains analyst at Advance Trading Australasia.
"South Korea sources up to half of their wheat imports from the U.S. so the fact they haven't found anything means they can be more confident ahead of the final results."
U.S. wheat futures fell immediately after news of the GM discovery broke last week, though have since recovered.
Chicago Board of Trade July wheat was trading up 0.32 percent at around $7.11 a bushel, after closing up slightly on Tuesday.
Although the United States has embraced genetically modified crops such as soybeans and cotton, genetically modified wheat has never been approved there, or anywhere else in the world.
South Korea - which last year sourced roughly half of its total wheat imports of 5 million metric tons from the United States - has also raised quarantine measures on U.S. feed wheat.
The U.S. has expanded its search team in Oregon as it hunts for the source of the unapproved wheat found growing wild on a farm there in April.
The U.S. Department of Agriculture announced the find last Wednesday after sophisticated tests to identify the wheat strain and says there is no evidence that any GM crops have entered the supply chain.