South Korea's air passenger traffic surged from a year earlier in September with both international and domestic passengers continuing to increase, the government said Thursday.

The number of international air passengers to and from the country spiked 21.7 percent on-year to over 5.99 million last month, with the number of domestic air passengers gaining 8.4 percent to 2.62 million, according to the Ministry of Land, Infrastructure and Transport.

Overall air passenger traffic jumped 17.3 percent to 8.62 million. The increase followed a 20.1 percent on-year spike in August.

The sharp increase in international air passengers was attributed to a large number of South Koreans going abroad during the traditional Chuseok holiday season, which fell on Sept. 14-16 this year.

Passengers between the country and Japan jumped 32.5 percent on-year to over 1.28 million in September, with passengers to and from Southeast Asian countries soaring 32.5 percent to 1.93 million, according to the ministry.

Of all international passengers to and from South Korea, 64.7 percent, or 3.87 million, used flights operated by the country's seven flag carriers, up from 64.3 percent a year earlier.

Advances by low cost carriers were far more visible.

The combined market share of five South Korean budget carriers came to 20.4 percent in September, up from 14.5 percent in the same month last year.

With the sharp increase in international passengers, the number of flights to and from South Korea also jumped 13.8 percent on-year to 37,227 in September.

International air cargo traffic surged 10 percent on-year to 317,931 tons. (Yonhap)