National Intelligence Agency investigators on Wednesday raided the homes and offices of lawmaker Lee Seok-ki and nine other members of the hard-left Unified Progressive Party on suspicion that they conspired to stage a rebellion.
NIS officials believe Lee was the head of a secretive revolutionary cell to which the others also belonged. All 10 have been slapped with travel bans and three have been arrested.
Lee's whereabouts were unknown as of Wednesday night. NIS officials said they discovered W100 million (US$1=W1,117) in cash in Lee's home and the source of the money is a mystery.
Earlier, the Suwon District Court issued arrest and search warrants. Lee cannot be arrested because he enjoys parliamentary immunity.
The NIS suspects that the cell consists of altogether 130 people who met at a religious center in Hapjeong-dong in northwestern Seoul in May and plotted to obtain firearms and sabotage key infrastructure to revolt against the state.
An NIS official said the agency has audio recordings proving the plot, including Lee instructing members of the cell.
An official at the Suwon District Prosecutors' Office said, the alleged cell has been under surveillance since 2010 and the NIS provided ample evidence to justify the warrants. The official added that the individuals have also been charged with spreading North Korean propaganda.