The lawyers for a former South Korean defence minister under investigation on insurrection charges said on Thursday a short-lived martial law decree imposed earlier this month was to raise alarm on opposition parties' abuse of the democratic process.

A probe into the top South Korean military intelligence commander's alleged involvement in martial law operations has been transferred to the military prosecution, the state anti-corruption investigation office said on Thursday.

South Korea's suspended President Yoon Suk Yeol did not respond on Wednesday to a second summons by anti-corruption authorities who, along with prosecutors, are investigating his short-lived martial law decree issued early this month.

South Korea’s President Yoon Suk Yeol again declined to appear for questioning by investigators over his martial law declaration as the embattled leader seeks to first defend himself at an impeachment trial.

I was pouring my cornflakes, still groggy from sleep, when my phone buzzed. The images stopped me cold: a division of heavily armed special forces deployed and UH-60 Black Hawk helicopters slicing through the night air at the National Assembly in Seoul.

The lawyers for South Korea's former defence minister who is under investigation on insurrection charges said on Thursday (December 26) that a short-lived martial law decree imposed earlier this month was to raise alarm on opposition parties' abuse of the democratic process.

President Yoon Suk Yeol listed numerous grievances against opposition lawmakers in an effort to justify his actions.

For the United States, the turmoil in South Korea is potentially disruptive to its geopolitical agenda in East Asia.

The prime minister is set to assume presidential powers on an interim basis. The constitutional court will now review the vote, which could take months.

The country’s opposition has accused acting president Han Duck-soo of obstructing justice and aiding the failed martial law bid.

South Korea's opposition said on Thursday it had filed an impeachment motion against acting leader Han Duck-soo, in an escalating row over the composition of the Constitutional Court that would decide whether to remove his predecessor from office.