At the Suwon District Court on Monday, prosecutors requested a 20-year prison term for left-wing lawmaker Lee Seok-ki, who stands accused of conspiring to stage a revolt in the event of an inter-Korean war.
Prosecutors also demanded that the 52-year-old lawmaker be stripped of his voting rights, and be restricted from holding public office for 10 years after his release from prison.
Prosecutors say the severe punishment befits the crime, as Lee had previously been arrested and prosecuted for a similar offense back in 2002.
They added that Lee has shown no remorse for his actions, and that he attempted to destroy the basic democratic order of South Korea in violation of Constitutional law.
Lee is currently standing trial on charges of leading a pro-North Korea group called the "Revolutionary Organization."
The underground group was allegedly plotting to overthrow the government by plotting to sabotage the South Korean government and U.S. troops in the event of an inter-Korean war.
In addition to Lee, prosecutors are seeking 10 to 15-year prison terms for six other Unified Progressive Party members who were indicted on the same charges.
Lee has consistently denied the insurrection charges against him.
A verdict in his trial is scheduled to come by the 17th of this month at the latest.
Observers say the ruling is likely to greatly influence the Constitutional Court's ruling on whether the leftist Unified Progressive Party should be disbanded.
The National Assembly is also currently reviewing a motion that calls for Lee Seok-ki to be removed from his parliamentary seat.
Park Ji-won, Arirang News.