Seoul, Dec 5 (IANS): South Korean Police on Thursday opened an investigation into charges President Yoon Suk Yeol committed treason by declaring martial law this week.

The investigation was assigned to the security investigation team under the National Office of Investigation of the National Police Agency after two complaints were filed, Yonhap news agency reported.

One complaint was filed by the minor opposition Rebuilding Korea Party, while the other was filed by a group of 59 activists.

The complaints accused not only Yoon but also former Defence Minister Kim Yong-Hyun, Army Chief of Staff Gen Park An-su and Interior Minister Lee Sang-min of treason and other related charges for their roles in the declaration and subsequent lifting of martial law on Tuesday.

The prosecution and the Corruption Investigation Office for High-ranking Officials have also received complaints accusing Yoon of treason and are reviewing whether to conduct their own investigations or transfer them to the police.

According to legal sources, Prosecutor General Shim Woo-jung has also ordered prosecutors to open their own investigation and assigned the case to a public security investigation division at the Seoul Central District Prosecutors Office.

On Wednesday, minor opposition parties, including the Labor Party, filed complaints against Yoon, Kim and Park with the prosecution, accusing them of treason.

With Shim's decision, both the police and prosecutors are expected to investigate the cases simultaneously.