A South Korean court has issued an arrest warrant for impeached President Yoon Suk Yeol, investigators said Tuesday, prompting hundreds of supporters to gather at the gates of his private residence.

Investigators probing Yoon over his 3 December declaration of martial law requested the warrant after he failed to report for questioning a third time.

By mid-afternoon Tuesday crowds were outside his home wielding placards and South Korean flags, chanting: "Martial law legal! Impeachment invalid!"

"The arrest warrant and search warrant... were issued this morning," the Joint Investigation Headquarters managing the probe into Yoon said in a statement.

It is unclear whether investigators and police will be able to execute the arrest because the Presidential Security Service (PSS) guarding Yoon have previously refused to comply with search warrants.

Yoon's legal team described the arrest order as "illegal and invalid" and have pledged to apply for an injunction to nullify it.

"I came out here because I was shocked and horrified that they're trying to arrest the president," said Song Mi-ja, a pro-Yoon protestor.

"The martial law was not an insurrection, what they're trying to do now is one," she told AFP.

Police were sent to the area in large numbers and could be seen shouting at protesters to keep in line, but a route in and out of Yoon's residence remained clear.

'Sufficient probable cause'

Yoon has been stripped of his presidential duties by parliament and faces criminal charges of insurrection, which could result in life imprisonment or even the death penalty.

"The arrest warrant and search and seizure warrant issued at the request of an agency without investigative authority are illegal and invalid," his lawyer Yoon Kab-keun said in a statement sent to AFP.

He said his client was not guilty of insurrection, adding that there was no intention of disrupting "the constitutional order" or to stage "an uprising".

But a Corruption Investigation Office official said there was "sufficient probable cause" to suspect Yoon commissioned a crime.

The warrant will be valid until Monday, the official told reporters, and Yoon will likely be held at the Seoul detention center.

"There is a concern that the individual may refuse to comply with summons without justifiable reasons," they said.

Investigators also raided the army's Counterintelligence Command offices on Tuesday and indicted two top commanders on charges they said were linked to insurrection and abuse of authority.

Lawyer Yun Bok-nam, president of Lawyers for a Democratic Society and who is not involved in the investigation, told AFP he predicted Yoon's arrest "will proceed smoothly" because the PSS has no legal standing to reject an arrest warrant.

But local media reported that an imminent arrest or search of the presidential residence was unlikely because investigators would seek to coordinate with the PSS. 

Technically, anyone obstructing the execution of an arrest warrant could be arrested.

Joint probe

Yoon is being investigated by prosecutors as well as a joint team comprising police, defense ministry and anti-corruption officials. 

A 10-page prosecutors' report seen by AFP said he authorized the military to fire weapons if needed to enter parliament during his failed martial law bid.

The report also said there was evidence that he had been discussing declaring martial law with senior military officials as early as March.

Yoon's lawyer had previously dismissed the prosecutors' report, telling AFP it was "a one-sided account that neither corresponds to objective circumstances nor common sense".

The suspended president declared martial law in an unannounced televised address, saying it was aimed at eliminating "anti-state elements" but lawmakers rushed to parliament to vote it down.

At the same time, heavily armed troops stormed the building, scaling fences, smashing windows and landing by helicopter.

A constitutional court will rule whether to uphold Yoon's impeachment.

The turmoil deepened late last week when Yoon's replacement, Han Duck-soo, was also impeached by parliament for failing to sign bills for investigations into his predecessor.

Finance Minister Choi Sang-mok has taken over as the new acting president and found himself thrust immediately into a disaster with the Jeju Air plane crash on Sunday that claimed 179 lives.

On Tuesday, Choi appointed two new judges to the constitutional court hearing Yoon's impeachment — meeting a key demand of the opposition.

by Hieun Shin and Cat Barton / AFP