South Korea arrests ex-defense minister Kim Yong-Hyun in treason charges over martial law

South Korean prosecutors on Sunday arrested former defence minister Kim Yong-Hyun amid a probe into alleged treason following President Yoon Suk Yeol implemented martial law, according to Yonhap News Agency.

Kim, who stepped down on Wednesday, was considered instrumental in Tuesday's temporary martial law implementation. According to a high-ranking military official and opposition members' impeachment documents, Kim had suggested the measure to Yoon.

Despite surviving Saturday's parliamentary impeachment vote following his brief martial law attempt, Yoon faces pressure from his own party leader who indicated the president's eventual resignation would be necessary.

According to the report, Kim voluntarily presented himself at the Seoul Central District Prosecutors' Office around 1.30 am on Sunday (10 pm on Saturday) for questioning by the special investigative team.

Three minor opposition parties submitted a legal complaint against Yoon, Kim and martial law commander Park An-Su, charging them with treason.

Yonhap reported that Kim is subject to a travel restriction while under investigation.

The national police are conducting a separate investigation into treason allegations against Yoon and senior ministers.

On Tuesday evening, Yoon startled the nation by granting extensive emergency authority to the military to eliminate what he termed "anti-state forces" and opposing political elements. He withdrew the order six hours later, after parliament collectively rejected the decree, despite military and police blockades.

The martial law crisis has created South Korea's most severe political upheaval in decades, endangering the democratic credentials of this significant US military ally and Asia's fourth-largest economy.