The peak summer holiday season is approaching and overseas vacationers should pay extra attention when returning home with expensive items as Korea's customs service will strengthen its monitoring of their luggage.

From Monday, up to 30 percent of all travelers’ baggage will be checked by customs officers, up from 3 percent at present. Officers will step up their inspections on randomly selected flights from major shopping destinations such as Hong Kong or Paris.

Those bringing in items exceeding the US$400 duty exemption limit will have to pay an additional 30 percent tax if they fail to declare such goods to customs.