South Korea's Supreme Court said it will rule on Thursday in a criminal case that could determine whether the frontrunner for the June 3 snap election, former opposition party leader Lee Jae-myung, can run for president.

South Korea's ousted leader Yoon Suk Yeol argued that his brief martial law declaration late last year was "not a coup d’etat" as he appeared in court on Monday.

South Korean President Yoon Suk Yeol, who declared martial law and had special forces storm the National Assembly, is removed from office.