A group of South Korean flour millers has issued a tender to buy 20,500 tonnes of US No 1 wheat, traders said on Tuesday. The tender would close at 2 pm (0500 GMT) on Wednesday, they added. Shipment is set between August 10 and September 10 and interested buyers are Daihen Flour Mills Co, Daesun Flour Mills Co and Samhwa Flour Mills Co.