The on-month rise marked a turnaround from four consecutive months of drop.

Foreign exchange reserves consist of securities and deposits denominated in overseas currencies, as well as International Monetary Fund (IMF) reserve positions, special drawing rights and gold bullion.

"The increase was mostly due to a rise in the value of assets held in non-U.S. dollar currencies, such as the euro and the British pound, along with an increase in the return on the held assets," the BOK said in a press release.

At the end of March, the euro changed hands with the U.S. greenback at $1.1335 per euro, up 3.9 percent from a month earlier, it added.As of the end of 2015, dollar-denominated holdings accounted for about two thirds of South Korea's overall foreign exchange reserves, with the rest held in other foreign currencies, the BOK said earlier. The central bank does not disclose the ratio of dollar and non-dollar holdings on a monthly basis.

The increase in foreign reserves apparently came mostly from overseas securities held in non-dollar currencies.

Foreign reserves held in overseas securities added $4.03 billion from the previous month to $340.53 billion as of end-March, while overseas deposits came to $20.3 billion, only gaining $500 million over the cited period.

The country's special drawing rights grew $300 million to $2.38 billion, while its reserve positions at the IMF shrank $300 million to $1.84 billion.

Holdings in gold bullion remained unchanged at $4.79 billion.

Meanwhile, the BOK said the country was the world's seventh-largest holder of foreign exchange reserves as of end-January, trailing China, Japan, Switzerland, Saudi Arabia, Taiwan and Russia, in that order. (Yonhap)