Yoon last week resisted arrest in a standoff between his guards and investigators after his short-lived power grab on December 3 plunged South Korea into its worst political crisis in decades.

Yoon’s Presidential Security Service (PSS) chief Park Chong-jun — a former police officer — submitted his resignation on Friday morning “as he attended a police questioning”, a PSS official told AFP.

It was later accepted by acting president Choi Sang-mok, an official from the interim leader’s office told reporters.

It came as a joint investigation team from the Corruption Investigation Office (CIO) and the police prepare to mount a new bid to arrest Yoon over his martial law declaration.

Park told reporters before being questioned at the Korean National Police Agency early Friday that there must be no violence if investigators attempt another arrest of Yoon.

“I believe that under no circumstances should there be physical clashes or bloodshed,” the former security chief said.

Choi later said in a statement sent to AFP that both ruling and opposition parties should “agree on establishing a special prosecutor investigation law” to find a way out of the crisis.

Rival protest camps in sub-zero temperatures are calling for Yoon’s impeachment to be declared invalid on one side, and for him to be immediately detained on the other.

Yoon would become the first sitting South Korean president to be arrested if investigators are able to detain him.

His legal team has said they will not comply with the current warrant.

1,000 investigators

The CIO said it will “prepare thoroughly” for the second arrest attempt and anyone obstructing them could be detained themselves.

Police on Friday held a meeting of top commanders to plan for the renewed effort, Yonhap news agency reported.

The National Office of Investigation, a police unit, sent a note to high-ranking police officials in Seoul requesting they prepare to mobilise 1,000 investigators for the fresh attempt, Yonhap reported.

Presidential security chief Park twice ignored police requests to appear for questioning over allegations of obstruction of public duty since his team blocked investigators.

Police then warned they would consider an arrest warrant if he did not submit.

“If I, as someone from the police, refuse the police’s summons, who among the citizens will agree to be investigated?” Park told reporters.

Tense standoff

Meanwhile, Yoon’s guards have increased security at his Seoul residential compound with barbed wire installations and bus barricades.

Yoon’s legal team said Friday the guards “remain on high alert 24/7” for another arrest attempt “despite immense pressure and stress”.

Separate from the insurrection probe, Yoon also faces ongoing impeachment proceedings — lawmakers have already suspended him, but the Constitutional Court will decide whether to uphold this or restore him to office.

The court has slated January 14 for the start of Yoon’s impeachment trial, which would proceed even in his absence.

Analysts have warned any violence during an arrest could hurt Yoon’s hopes of survival.

“Physical confrontations would… likely weaken his position in the upcoming impeachment trial,” political commentator Park Sang-byung told AFP.

Polls show approval ratings for Yoon’s ruling party have been rising as the crisis drags on.

A new Gallup survey published Friday showed the People Power Party’s approval rating had risen to 34 percent from 24 percent three weeks ago.