South Korea's current account surplus widened in September from the previous month as exports expanded at a faster rate than imports weathering the local currency's gain, the central bank said Tuesday.

The current account surplus reached US$6.07 billion in September, up from a revised $2.5 billion in the previous month, according to the Bank of Korea (BOK). The current account is the broadest measure of cross-border trade.

The September figure was the largest monthly surplus since a record high of $6.14 billion in July, and September marked the eighth straight month of surplus.

In the first nine months of this year, the cumulative current account surplus reached $28.5 billion, while the central bank has revised its full-year surplus estimate up to $34 billion from $20 billion.

Despite weaker exports and the slowing growth, the local currency has appreciated more than 5 percent to the dollar so far this year as foreign capital continued to flow into Korea amid quantitative easing by major economies.

Exports, which account for about 50 percent of the local economy, remained fragile on the global economic slowdown. Imports are also falling as domestic demand is weakening.

The BOK calculates the value of exports by marking cash flows generated in the course of the ship building as overseas shipments, leading trade gains to remain different from the value of customs-cleared exports. On a customs-cleared basis, exports posted an on-year decline for the third month in a row in September.

The BOK said that the surplus of goods balance hit an all-time high of $5.64 billion in September as exports rose at a faster pace than imports.

Overseas shipments rose 1.1 percent on-year to $47.72 billion while imports fell 6.7 percent to $42.1 billion.

The service account, which includes outlays by South Koreans on overseas trips, posted a surplus of $323.3 million last month, a turnaround from a shortfall of $262.2 million in August.

The primary income account, which tracks wages for foreign workers and dividend payments overseas, logged a surplus of $203.9 million in September, down from $435.5 million in August.

Meanwhile, the capital and financial account, covering cross-border investments, posted a net outflow of $5.2 billion in September, compared with a net outflow of a revised $613 million the previous month, the central bank said. (Yonhap News)