The won closed up W2.3 on Tuesday at W1,022.1 against the U.S. dollar, the highest in almost six years. Traders had expected the Korean currency to remain steady following verbal intervention by forex authorities who worry that a further strengthening of the won could hurt the price competitiveness of Korea's exports.
"It's not easy to respond since it's due to structural causes like the current account surplus and a weak dollar," said one forex official.
Since breaching the W1,050 barrier on April 9, the won has been strengthening steadily against the dollar. In just one month, it has strengthened around three percent.
The won also rose against the Japanese yen on Tuesday, closing at W999.41 per 100 yen and breaching the psychologically-important W1,000 level for the first time in four months.