The figure represents a surplus for 64 months in a row. The current account is the biggest measure of cross-border trade.

The BOK said the widened deficit in the travel balance and increased imports of machinery were to blame for the narrowed current account surplus.

The BOK said the travel balance deficit widened to $1.39 billion in June from a deficit of $740 million a year earlier due to a rise in overseas trips. The June figure marked the highest travel balance deficit since July 2015, when the travel balance deficit stood at $1.47 billion.

The number of outbound tourists jumped 18 percent on-year to more than 2.09 million in June, while foreign visitors to South Korea fell 36.2 percent to 992,000. Among foreign visitors, the number of Chinese travelers came to 255,000 in June, down 66.4 percent from a year earlier.

China -- South Korea's largest trading partner -- has imposed restrictions on South Korean imports and banned the sale of group tour packages to South Korea in protest of the deployment of an advanced US missile defense system in South Korea.

Seoul and Washington said the Terminal High Altitude Area Defense system is only meant to counter North Korea's evolving nuclear and missile threats. But China has repeatedly pressed South Korea to withdraw the THAAD missiles out of concern that the deployment could hurt Beijing's security interests.

The primary income account surplus came to $550 million in June from a surplus of $1.09 billion a year earlier.

Exports rose 6 percent on-year to $47.99 billion, with imports surging 18 percent to $38.28 billion. (Yonhap)