A total of 49, including 21 who were disguised as defectors, have been arrested over the past 10 years on charges of spying for North Korea.
In a report submitted to the National Assembly, the Justice Ministry said the 49, taken into custody since 2003, included 14 under the Roh Moo-hyun administration and 31 when former President Lee Myung-bak was in office until the beginning of this year.
Through this year alone, under the new Park Geun-hye administration, there have been four arrests on charges of espionage on behalf of North Korea.
Interestingly enough, the number of arrests have been increasing at a rapid pace since 2010, rising to 11 following just two in 2007-2009, eight in 2011 and nine last year, the ministry report said.
Among the responsibilities of the accused were securing classified national security information, transporting North Korean defectors back home and planning the assassination of specified targets.
In particular, it is believed that three North Korean agents were dispatched to the South for the purpose of planning the assassination of senior North Korean official Hwang Jang-yeop.
"We have discovered that numerous senior North Korean agents disguised their defection to the South, raising the need to more effectively monitor and evaluate the histories and identities of potential defectors," one ministry official said.