Former minor party leader Cho Kuk (center) speaks before being imprisoned at the Seoul Detention Center, south of Seoul, on Monday, to begin his two-year prison sentence. (Yonhap)

Former minor party leader Cho Kuk on Monday called for an all-out effort for regime change before being imprisoned at the Seoul Detention Center to begin his two-year prison sentence.

Cho, who led the minor opposition Rebuilding Korea Party, has lost his parliamentary seat after the Supreme Court upheld his conviction last Thursday on charges of academic fraud involving his children and unlawful interference in a government inspection.

He told reporters and supporters in front of the detention center that his party should make all possible efforts to prevent the ruling People Power Party, an alleged accomplice in impeached President Yoon Suk Yeol's martial law declaration, from maintaining power.

About 100 supporters gathered to see Cho off as he entered the prison. (Yonhap)