South Korea's international air passenger traffic jumped 12.1 percent from a year earlier last month, helped by a sharp increase in passengers to and from Japan and other Asian countries, the government said Monday.

International air passengers to and from the country came to about 6.96 million in January, compared with 6.21 million in the same month last year, according to the Ministry of Land, Infrastructure and Transport.

Air passengers between South Korea and Japan spiked 19.7 percent on-year to some 1.59 million, while international passengers to and from Southeast Asian nations surged 13.6 percent to about 2.68 million.

Passengers to and from China gained 4.5 percent to some 1.53 million amid growing tension between South Korea and China over Seoul's plan to deploy a US missile defense system, the Terminal High Altitude Area Defense or THAAD.

The combined market share of South Korean flag carriers inched up to 66.1 percent from 65.7 percent a year earlier.

The rise, however, has been attributed to advances by low cost carriers, whose international passengers spiked 48.3 percent on-year to nearly 1.68 million in January.

International passengers of two full-service carriers -- Korean Air and Asiana Airlines -- slipped 0.9 percent to 2.92 million, according to the ministry.

In January, the country's overall air passenger traffic jumped

12.6 percent on-year to some 9.49 million with its domestic air passenger traffic also surging 14.2 percent to about 2.53 million.

International air cargo traffic grew 9.5 percent on-year to about 320,000 tons. (Yonhap)