South Korea's foreign-exchange reserves rose to a fresh record high in October, aided by a weak U.S. dollar and an increase in investment profit, the central bank said Tuesday.

The country's foreign reserves totaled a record $343.23 billion as of end-October, up $6.3 billion from the previous month, according to the Bank of Korea (BOK).

The October gain also marked the largest monthly growth since October 2011 when the FX reserves rose by $7.59 billion.

The foreign reserves rose for the fourth straight month in October after declining by the largest amount in 13 months in June.

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

The BOK said that a weaker U.S. dollar boosted the dollar-conversion value of non-dollar assets and investment profit also rose.

The euro appreciated 1.7 percent to the U.S. dollar last month and the Australian dollar gained 1.7 percent per the greenback.

The country's growing FX reserves and the current account surplus serve as buffers for South Korea at a time when some emerging countries had been suffering from foreign capital flight and currency depreciation, triggered by speculation over U.S. stimulus tapering.

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