South Korean police have raided the presidential office over President Yoon Suk-yeol's martial law decalaration, Yonhap news agency reported on Wednesday.
Yoon is the subject of a criminal investigation on insurrection charges over his short-lived imposition of martial law but he has not been arrested or questioned by authorities.
Former South Korean Defence Minister Kim Yong-hyun, who is accused of playing a lead role in the failed imposition of martial law on December 3, has tried to commit suicide inside a detention centre, a justice ministry official told parliament.
South Korea's police chief became the latest top official to be arrested, Yonhap news agency said on Wednesday.
The main opposition Democratic Party (DP) said on Wednesday it plans to hold a parliament vote to impeach Yoon on Saturday, with some members of the president's People Power Party (PPP) having spoken out in favour of such a motion.
"The impeachment train has left the platform. There is going to be no way to stop it," DP leader Lee Jae-myung said at the start of a party meeting.
The first impeachment vote last Saturday failed as most PPP members boycotted the session.
Yoon's surprise martial law declaration stunned the country and plunged Asia's fourth-largest economy and a major U.S. ally into a leadership crisis, sending shockwaves through diplomatic and economic fronts.
National Police Commissioner Cho Ji-ho was arrested early on Wednesday on insurrection charges, Yonhap said. Cho is accused of deploying police to block lawmakers from entering parliament after Yoon declared martial law.
Soon after Yoon's surprise late-night declaration, lawmakers including some members of his own party defied the security cordon around parliament and voted to demand the president immediately rescind martial law, which he did hours later.

Damascus cafe blast kills 5, wounds 16
Rebels in Indonesia's Papua kill American pilot, burn plane
Russian air strikes kill 10, injure more than 50 in Ukraine's Kyiv
Firefighters battle wildfire in southern France
US, Iran talks conclude in Doha, focused on Strait of Hormuz
Trump honours Theodore Roosevelt in North Dakota, debuts new Air Force One
Kenyan court charges 8 schoolgirls with fellow students' murder
At least 5 people killed in fire in Antwerp apartment block
