The country's FX reserves stood at $423.16 billion as of the end of December, up $7.06 billion over a month, according to the Bank of Korea. It marked the biggest monthly increase since November 2020.

The increase resulted from larger foreign deposits of financial institutions and converted value of non-dollar assets, despite a downside effect from the FX swap programme with the country's pension fund, according to the BOK.

The U.S. dollar index, a measure of the greenback's value against six major currencies, fell 2.3% in the last month of 2022.

(Reporting by Jihoon Lee, editing by Ed Osmond)