A South Korean court has issued an arrest warrant for impeached, suspended President Yoon Suk Yeol, investigators said Tuesday, over his short-lived bid to impose martial law on the country.

Yoon briefly suspended civilian rule this month, plunging South Korea into its worst political crisis in decades.

He was stripped of his presidential duties by parliament over the action, but a constitutional court ruling is pending on whether to confirm the impeachment.

"The arrest warrant and search warrant for President Yoon Suk Yeol, requested by the Joint Investigation Headquarters, were issued this morning," the Joint Investigation Headquarters said in a statement.

The conservative leader faces criminal charges of insurrection, which could result in life imprisonment or even the death penalty.

Investigators probing Yoon over his declaration of martial law requested the warrant Monday after the suspended president failed to report for questioning a third time.

"The reason for the warrant is that there is a concern that the individual may refuse to comply with summons without justifiable reasons, and there is sufficient probable cause to suspect the commission of a crime," a Corruption Investigation Office (CIO) official told reporters at a briefing on Tuesday.

"The warrant is valid until January 6," the official said, adding that Yoon could be held at a police station or the Seoul detention center.

Yoon's lawyer called the arrest warrant for the impeached president "illegal and invalid," saying investigators lacked the authority to probe the president.

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

Arrest? Even though the warrant has been issued, it is unclear whether investigators and police will be able to execute it.

The Presidential Security Service has previously refused to comply with three search warrants.

It said Tuesday that "security measures regarding the execution of the warrant will be carried out in accordance with lawful procedures," in a statement to local media.

But lawyer Yun Bok-nam, president of Lawyers for a Democratic Society, told AFP that while there was a legal basis for rejecting a search warrant "there's no such provision for arrest warrants."

"I expect the (arrest) process will proceed smoothly," he said, adding that warrants were typically valid for seven days and had to be executed within that time frame.

Police were deployed early Tuesday outside Yoon's residence in central Seoul, in a likely bid to head off scuffles.

Yoon's supporters and protesters calling for his removal have both staked out his residence, with local media running images of altercations between the two camps overnight.

"Up to 3,000 people will move to protest against the unfair and invalid arrest warrant," said an official from the largest protest group supporting Yoon.

Local media reported that an imminent arrest or search of the presidential residence was unlikely, as investigators would seek to coordinate with the presidential security service.

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 stated that Yoon authorized the military to fire weapons if needed to enter parliament during his failed martial law bid.

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."

Yoon declared martial law in an unannounced televised address on December 3, saying it was aimed at eliminating "anti-state elements."

Lawmakers rushed to parliament within minutes of the declaration to vote it down.

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

According to the prosecution indictment report, Yoon told the chief of the capital defense command, Lee Jin-woo, that military forces could shoot if necessary to enter the National Assembly.

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

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

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 Sunday that claimed 179 lives.