Korean Air Lines Co., South Korea's leading airline, said Wednesday that it swung to a net loss in the third quarter due to increased fuel costs and a weakening local currency.

Net loss came to 524.3 billion won (US$463.6 million) in the July-September period, compared with a profit of 550.7 billion won a year earlier, the company said in a regulatory filing.

Sales rose 4.3 percent to 3.3 trillion won over the same period, while operating profit plunged 46.5 percent on-year to 239.3 billion won.

Korean Air said that the third-quarter loss was attributable to high fuel costs, which surged 33.9 percent on-year during the cited period and accounted for over 40 percent of the company's total expenses.

Jet fuel prices were also driven up by the weakening Korean won, which has fallen sharply against the U.S. dollar, losing some 10 percent last month.

Its international passenger traffic during the third quarter rose 10.6 percent, underpinned by an increased number of travelers from China and Japan. But cargo volume fell 5.9 percent due to the global economic recession and a slump in shipments of electronic devices exported by South Korean companies.

"We will mobilize jumbo airliners such as the A-380 and B777-300ER into popular routes in an effort to increase sales," Korean Air said in a statement. "We will improve profitability of our cargo lines by seeking better routes and markets."

Shares of Korean Air closed at 49,800 won on the Seoul bourse, up 2.68 percent from the previous session's close. The third-quarter business results were released before the market closed.