Yoon, a former prosecutor, plunged democratic South Korea into political turmoil when he declared martial law on Dec 3, suspending civilian rule and sending soldiers to parliament.

His attempt to impose martial law only lasted around six hours as the opposition-led parliament defied armed troops to vote it down and later impeached him over the move.

As part of a separate criminal probe, Yoon was detained in a dawn raid in mid-January on insurrection charges, becoming the first sitting South Korean head of state to be arrested.

He is being held in detention but has been attending impeachment hearings at the constitutional court, which will determine whether his impeachment is upheld.

If the court upholds the impeachment, an election must be held within 60 days to elect a new president.

A convoy of black SUVs arrived at the court today, carrying Yoon to attend a hearing scheduled to begin at 2pm.

At previous hearings, Yoon denied instructing top military commanders to “drag out” lawmakers from parliament to prevent them from voting down his decree, a claim refuted by opposition MPs.

He has argued that he did not believe the short-lived martial law was a “failed martial law”, but rather one that “ended a bit sooner” than he expected.

During today’s hearing, two former military commanders and an ex-spy agency official are set to testify as witnesses.

Hong Jang-won, a former deputy director of the National Intelligence Service, testified before lawmakers that he had been ordered to arrest politicians – a claim that contradicts Yoon’s denial of such an order.

Yoon, 64, was indicted in January, with prosecutors accusing him of being a “ringleader of the insurrection”.

He faces a separate criminal trial on those charges.

Insurrection is not covered by presidential immunity.

If convicted, he faces jail time or the death penalty.