South Korea's foreign exchange reserves rose to a new high last month on a rise in returns on foreign assets.

According to the Bank of Korea on Wednesday, the total value of the country's foreign exchange reserves came to 409-point-65 billion U.S. dollars at the end of January, up 840 million dollars from a month earlier.

The central bank explained that in spite of a drop in the U.S. dollar value of reserves held in other foreign currencies, earnings from operating foreign exchange assets increased. 

South Korea was the world's ninth-largest holder of foreign exchange reserves at the end of December, with China topping the list, followed by Japan and Switzerland.