South Korean prosecutors indicted detained President Yoon Suk Yeol on charges of leading an insurrection with his short-lived imposition of martial law that plunged the nation into a political crisis.

With the indictment, Yoon, who is also facing an impeachment trial, has become the first sitting president in South Korea's history to be indicted under detention, reported Yonhap news agency.

Yoon is now facing the allegation of conspiring with former Defense Minister Kim Yong-hyun and others to incite an insurrection last month by declaring an emergency.

He was also alleged to have deployed military forces to parliament in an attempt to prevent lawmakers from voting against martial law.

Yoon is also accused of planning to arrest and detain key political figures, including National Assembly Speaker Woo Won-shik and heads of rival parties, as well as officials of the election watchdog, Yonhap reported.

Yoon Suk Yeol was officially arrested on January 19.

Yoon had denied all allegations levelled against him.

He was voted to be impeached by the Parliament.

“Based on the investigation so far, there are no grounds to consider any change to the arrest warrant issued against the president,” prosecutors said in a statement Sunday as quoted by CNN, adding that “sufficient evidence exists to substantiate the charges.”

According to reports, if convicted of leading an insurrection, Yoon could face life imprisonment or even the death penalty.

Under South Korean law, a sitting president has immunity from most criminal prosecutions, but the privilege does not extend to allegations of insurrection or treason, reported CNN.