The National Intelligence Service on Thursday arrested United Progressive Party lawmaker Lee Seok-ki on charges of plotting a rebellion. This is the first time an incumbent lawmaker has been arrested on such charges.
The Suwon District Court issued the arrest warrant on Thursday evening, accepting a police argument that he could seek to destroy evidence and go into hiding.
As he was being hauled off to jail, Lee denied the charges saying they had been fabricated.
On Wednesday, lawmakers had voted to lift Lee's parliamentary immunity.
The NIS accuses him of heading a secretive cell of some 130 members of his hard-left party and discussing at a meeting in May how to sabotage key installations here should war break out with North Korea.
The NIS will investigate whether Lee received his orders from North Korea and will investigate whether other UPP members were involved in the plot. Three others have already been arrested in connection with the alleged plot.