South Korean opposition parties introduced a bill Thursday calling for an independent investigation into impeached President Yoon Suk Yeol’s brief martial law declaration, as thousands of his supporters and critics held tense rallies near his residence ahead of his potential detention.

It was unclear when and how police could make the arrest and whether the presidential security service, which has blocked access by investigators with a search warrant to Yoon's office and official residence,

The police are investigating whether President Yoon Suk Yeol tried to lead an insurrection when he declared martial law and plunged the country into crisis.