Korean Air Co., South Korea's leading carrier, said Wednesday its second-quarter net profit fell 6 percent on-year due to an increase in fuel and labor costs.Net profit for the three months ending in June reached 349 billion won (US$251.2 million), compared with 371.5 billion won during the same period of last year, the company said in a statement.Operating profit fell 12 percent to 413.4 billion won from 468 billion won a year ago. Sales jumped 14 percent on-year to 4.02 trillion won from last year's 3.53 trillion won tally.The company attributed its quarterly performance to increased fuel and labor costs, and other expenses associated with higher business volume.The airline said sales from the passenger business rose by 10 percent on-year thanks to the airline's expanded capacity across its networks, including China, and strong business and leisure demand to the Americas and Europe.Korean Air said it aims to maximize profit by increasing flight frequencies and expanding charter operations during the peak summer travel months in the third quarter.Source: Yonhap News Agency