Members of the Korean Confederation of Trade Unions (KCTU) were arrested by the police Tuesday after illegally occupying the Supreme Public Prosecutors' Office building in southern Seoul. The KCTU members occupied the building to demand that prosecutors conduct an investigation into Hyundai Motor and Kia Motors over allegations that they illegally dispatched contract workers and are refusing to transition contract workers to permanent positions. The Seoul Metropolitan Police Agency arrested six of the nine members who refused to leave the building and took them into custody for investigation. It released them at around midnight. A total of nine high-ranking KCTU officials participated in Tuesday's protest, including Lee Byeong-hoon, the KCTU head at Hyundai Motor, and Kim Su-eok, the union's leader at Kia Motors. The sit-in they staged at the lobby of the building lasted for eight hours before they were removed by the police. During the sit-in, around 130 KCTU members assembled outside the building and staged their own protest, demanding that police look into the allegations against Hyundai and Kia. "Hyundai Motor, Kia Motors and GM Korea are all currently illegally dispatching contract workers while also refusing to upgrade these same workers to the permanent payroll," said Lee. "We demand an investigation into these illegal labor practices and time to talk with Prosecutor General Moon Moo-il about the situation." Some members of the sit-in also held signs that demanded the Asahi Glass Corporation comply with a 2017 court order that contract workers be upgraded to permanent positions. Others held signs that called for the arrest of Hyundai Group Chairman Chung Mong-koo and Hyundai Motor Group Vice Chairman Chung Eui-sun. The KCTU has focused on demonstrations at government agencies this week. On Wednesday, the KCTU staged a sit-in in front of the Blue House, demanding that the government abolish contract positions. GM Korea's labor union also staged a sit-in at Rep. Hong Young-pyo's office in Bupyeong, Incheon on Tuesday over the company's plan to spin off its R&D wing. Hong, the floor leader of the ruling Democratic Party, condemned the union, saying, "staging a sit-in like this is considered terror in the United States." "We have always adopted a violent means of protest," said the GM Korea labor union members in response. This is not the first time that a GM Korea labor union illegally occupied governmental facilities. GM Korea's contract workers union staged a second sit-in at the Ministry of Employment and Labor's Changwon office on Monday to protest the fact that the automaker did not follow the ministry's guidelines and directly hire all the 774 contract workers at GM Korea's factories in Changwon.