The country's foreign reserves rose to a fresh high in September mainly because the U.S. dollar remained weak against major currencies, the central bank said Friday.

The country's foreign reserves reached $322.01 billion as of the end of September, up $51.3 billion from the previous month, according to the Bank of Korea (BOK).

The central bank attributed the September rise largely to the appreciation of the euro and the pound against the greenback.

"The dollar conversion value of assets denominated in the euro and the pound surged last month due to the greenback's weakness," the BOK said. "Also responsible was a rise in profits from foreign currency assets."

Last month, the euro appreciated nearly 0.7 percent on-month to the dollar and the British pound rose 0.2 percent against the greenback.

Foreign reserves consist of securities and deposits denominated in overseas currencies, along with International Monetary Fund reserve positions, special drawing rights and gold bullion.

As of end-August, South Korea was the world's seventh-largest holder of foreign exchange reserves. (Yonhap)