Parcels from overseas shopping sites multiplied by 40 percent last year as more Koreans became aware of better deals online. Incheon airport customs on Sunday said over 10 million international parcels from online shopping sites abroad were received in 2013, up 40 percent from 2012.
In 2008, the number was just 1.95 million, 29 percent of all international parcels by couriers, but that proportion has risen to 69 percent.
Most were clothing, shoes, cosmetics and dietary supplements.
As of the end of 2013, 80 percent came from the U.S. During the bargain sales period in the U.S. including Black Friday and the year-end season, the volume surged 28 percent.
The number of illegal drugs smuggled via international couriers and detected by the customs also rose from 22 parcels in 2011 to 50 in 2013.
A customs official said the agency will toughen monitoring.