The government said Friday that it has strengthened its inspection of U.S. wheat imports following the discovery of unapproved genetically modified wheat in Oregon.

Currently, the country inspects a 1-kilogram sample from each shipment of U.S. wheat, according to the Ministry of Agriculture, Food and Rural Affairs.

Starting Friday, the government plans to test additional samples of 1 kilogram from each container of U.S. wheat, it said.

The move comes one day after the U.S. Animal and Plant Health Inspection Service confirmed unapproved genetically modified wheat has been found in an Oregon field.

The U.S. Department of Agriculture said there was no evidence that genetically engineered wheat entered the U.S. market. However, the Seoul government said a precautionary measure was inevitable as Oregon exports nearly 90 percent of its wheat produce.

"The Animal and Plant Quarantine Agency inspects each shipment of agricultural products, including wheat, for pests and genetically modified (GM) substances," a ministry official said.

"No GM substance has been found so far."

Still, the local flour milling industry said it will stop using U.S. wheat at least for the time being.

"In regard to the announcements by the U.S. Agriculture Department and Animal and Plant Quarantine Agency that unapproved GM wheat has been discovered in a farm in Oregon, milling companies here will temporarily stop purchasing U.S. wheat until the outcome of a thorough investigation by the quarantine office comes out," an association of local millers said in a released statement.

South Korea imported some 1.2 million tons of wheat from the United States in 2012 for animal feed. (Yonhap News)