In scenes of high drama on Friday, Yoon Suk Yeol's presidential guards and military troops shielded the former star prosecutor from investigators, who called off their arrest attempt citing safety concerns.

The South Korean president was impeached and suspended last month after the bungled martial law declaration — a political move swiftly overturned by parliament — with a separate warrant later issued for his arrest.

"There was a standoff. While we estimated the personnel blocking us to be around 200, there could have been more," an official from the investigation team said Friday on condition of anonymity.

"It was a dangerous situation."

Yoon faces criminal charges of insurrection, one of a few crimes not subject to presidential immunity, meaning he could be sentenced to prison or, at worst, the death penalty.

If carried out, the warrant would make Yoon the first sitting president ever arrested.

Since his impeachment, Yoon has holed up in his presidential residence in the capital Seoul, where he has refused to emerge for questioning three times.

The unprecedented showdown — which reportedly included clashes but no shots fired — left the arrest attempt by investigators in limbo with the court-ordered warrant set to expire on Monday.

Officials from the Corruption Investigation Office (CIO), which is probing Yoon over his martial law decree, said there could be another bid to arrest him before then.

But if the warrant lapses, they would have to apply for another from the same Seoul court that issued the initial summons.

The Constitutional Court slated 14 January for the start of Yoon's impeachment trial, which if he does not attend would continue in his absence. 

Former presidents Roh Moo-hyun and Park Geun-hye never appeared for their impeachment trials.

Yoon's lawyers decried Friday's arrest attempt as "unlawful and invalid," and vowed to take legal action.

Experts said investigators could wait for greater legal justification before attempting to arrest the suspended president again.

"It may be challenging to carry out the arrest until the Constitutional Court rules on the impeachment motion and strips him of the presidential title," Chae Jin-won of Humanitas College at Kyung Hee University told AFP.

Stable path

South Korean media reported that CIO officials had wanted to arrest Yoon and take him to their office in Gwacheon near Seoul for questioning.

After that, he could have been held for up to 48 hours on the existing warrant. Investigators would have needed to apply for another arrest warrant to keep him in custody.

Yoon has remained defiant despite the political impasse he initiated with his 3 December decree.

He told his right-wing supporters this week he would fight "to the very end" for his political survival.

By the time investigators attempted to execute the warrant for Yoon's arrest, he had layered his presidential compound with hundreds of security forces to prevent it.

Around 20 investigators and 80 police officers were heavily outnumbered by around 200 soldiers and security personnel linking arms to block their way after entering the presidential compound.

A tense six-hour standoff ensued until early Friday afternoon when the investigators were forced to U-turn for fear of violence breaking out.

The weeks of political turmoil have threatened the country's stability.

South Korea's key security ally, the United States, called for the political elite to work towards a "stable path" forward.

National Security Council spokesman John Kirby reaffirmed Washington's commitment to maintaining bilateral ties and readiness to respond to "any external provocations or threats."

Outgoing US Secretary of State Antony Blinken is scheduled to hold talks in Seoul on Monday, with one eye on the political crisis and another on nuclear-armed neighbour North Korea.