South Korea's current account surplus hit the lowest in four months in August due to slowing exports and increased imports, central bank data showed Tuesday.

The current account surplus reached $5.51 billion in August, compared with $8.67 billion in July, according to the preliminary data from the Bank of Korea.

The August figure represents a drop from an $8.54 billion surplus from a year earlier and also marks the lowest in four months. The current account is the biggest measure of cross-border trade.

In August, the size of the surplus in the goods account came to $7.3 billion, down from a $10.78 billion surplus in the previous month, the BOK said.

It said the service balance narrowed its deficit to $1.45 billion from $1.53 billion from a month earlier.

In the primary income account, the country posted a surplus of $610 million in August, sharply up from $500 million in the previous month.

Exports increased 2.6 percent on-year to $40.12 billion in August, while imports gained 0.7 percent to $35 billion. (Yonhap)