A South Korean court on Monday sentenced an opposition legislator to 12 years in prison after a rare treason trial saw him convicted of plotting an armed revolt in support of North Korea. Prosecutors had demanded 20 years for Lee Seok-ki, 52, who was tried along with six other members of his left-wing United Progressive Party. They were sentenced to terms ranging from four to 12 years. Lee was the first member of the National Assembly (parliament) to face treason charges since the country’s transformation from a military-backed autocracy to a fully-fledged democracy in the 1980s. As well as his prison term, the court ordered Lee deprived of his civil rights for 10 years following his eventual release. After parliament voted to lift his immunity from arrest, Lee was charged last September under the 65-year-old National Security Law, which rights groups have accused past administrations of using to stifle debate and silence political opposition. The charges related to meetings Lee held with his supporters in May last year, at a time of surging military tensions following the North’s third nuclear test. The court was told how Lee had told members of his group to prepare attacks on South Korea’s communication lines and railways in case of a full-scale conflict breaking out with the North. “We see sufficient evidence that (the defendant) plotted a revolt and planned collective actions to carry it out,” said the court ruling. The trial also heard how Lee had made remarks sympathetic to North Korea and sung North Korean “revolutionary” propaganda songs at the meetings. Lee steadfastly denied all the charges, saying he was the victim of a “witch hunt” by South Korea’s spy agency aimed at deflecting public attention from a scandal involving a number of its agents meddling in the 2012 presidential election. The constitutional court has yet to make a decision on a government petition to disband the United Progressive Party, which fielded a candidate in the 2012 ballot. Lee has been in trouble for his political views before. In 2002 he was sentenced to two and a half years for anti-government activities. He received a presidential pardon later the same year. The National Security Law, which bans any activity that praises or encourages North Korean political ideals, was adopted in 1948 with the establishment of the Republic of Korea (South Korea). Its stated aim was to protect the fledgling government against espionage and other threats from a belligerent North Korea. The United Nations has been calling for decades for the reform of the legislation, criticising its use to counter political dissent. An Amnesty International report in 2012 highlighted what it described as an emerging trend of invoking the law against individuals and groups that had no tangible pro-North Korea stance.