"The won's gain is too fast. We will take appropriate measures, if necessary," Deputy Financial Minister Kim Sung-jin told an interview on a radio program.

The Yonhap News quoted another unnamed official as saying that"We have ample ammunition for market sterilization.""Some say the currency authorities will sit idle, but we will take(action) at an appropriate time."

The exchange rate reached an eight-year high on Monday at 939.80 won to one U.S. dollar.

Won has gained more than 6 percent against US dollar during the past four months this year. In 2005, it rose 3 percent against U.S. dollars. Economists are worrying the strong won would bring negative effects to the country's exports.

South Korea's central bank said each percentage-point rise by the won against the U.S. dollar results in a 520 million-U.S. dollar cut in the nation's current account surplus. Enditem