Police referred the leader of South Korea's second-largest umbrella labor union to the prosecution for further investigation over last month's violent rallies in downtown Seoul, police officials said Friday.

Han Sang-gyun, the head of the Korean Confederation of Trade Unions, is accused of orchestrating a massive anti-government protest on Nov. 14 that led to a violent clash with the police.

The labor union leader faces nine charges, including disruption of the execution of public duty and damage of public property.

Police said they have additionally applied a charge of sedition against Han, the first time in nearly 30 years.

The crime of sedition refers to "the act of destruction through assault or intimidation by gathering multiple forces."

By law, police can initiate preliminary investigations on their own but should be under the supervision of the prosecution. Also, prosecutors have the sole right to charge suspects.

The last time investigative authorities charged a suspect with sedition was in 1986 when protesters violently clashed with police in the western port city of Incheon.

The KCTU chief turned himself in to police last week after hiding out at Jogye Temple in central Seoul since Nov. 16. (Yonhap)