Thousands of South Koreans protest as president digs heels in

Protesters attend a rally against impeached South Korean President Yoon Suk Yeol in Seoul on January 11, 2025. [AFP]

Thousands of South Koreans gathered for rival demonstrations in the capital on Saturday, as investigators prepare another attempt to arrest suspended President Yoon Suk Yeol over his short-lived martial law decree.

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

Protesters both for and against Yoon were scheduled to gather in sub-zero conditions along major roads in the centre of Seoul on Saturday -- either demanding his arrest or calling for his impeachment to be declared invalid.

The country has bristled with tension for weeks after Yoon directed soldiers to storm parliament, where they unsuccessfully tried to prevent lawmakers from voting down martial law. Since being impeached, Yoon has battened down the hatches.

"Despite our efforts, he continues to evade accountability, and both the police and the CIO (Corruption Investigation Office) have really failed to act decisively," said anti-Yoon protester and student Kim Min-ji, 25.

"It is crucial for us to raise our voices until he is removed from office."

Yoon supporter Su Yo-hahn, 71, said the sitting president's martial law declaration which he alleged was to root out anti-state forces had "valid reasons."

"He is someone who was elected by the people and represents our country. Saving Yoon is the way to save our nation," said Su.

Brandon Kang, a 28-year-old Yoon supporter, told AFP he liked the president because he found him "quite similar to US President-elect Donald Trump, which I really... appreciate."

Yoon's supporters rallied outside his residence before major demonstrations on both sides were held in central Seoul.

The pro-Yoon side waved South Korean flags while rainbow headbands were seen on the side advocating his removal.

If the warrant is executed, Yoon would become the first sitting South Korean president to be arrested.

His presidential security chief Park Chong-jun resigned Friday as he faced questioning over why his guards blocked Yoon's arrest.

The presidential security service guards including military troops shielded Yoon from investigators in a six-hour standoff.

Park was again being questioned on Saturday while acting PSS chief Kim Seong-hun refused to turn up to a third summons, opening him up to possible arrest.

"Kim Seong-hun... cannot leave his post for even a moment regarding presidential security matters," the PSS said in a statement.

Kim, who is considered to be more of a hardliner than his predecessor Park, is expected to lead efforts to prevent the execution of the second arrest warrant, if he avoids being arrested.

Lee Jin-ha, the PSS head of security and safety, also appeared for police questioning on Saturday.

The CIO said it will "prepare thoroughly" for its second attempt to arrest Yoon and warned that anyone obstructing them could be detained.

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 news agency reported.

Meanwhile, Yoon's guards have reinforced his Seoul compound with barbed wire installations and bus barricades.

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 decision 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.

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

On Friday, opposition parties submitted a resolution demanding the expulsion of a ruling People Power Party lawmaker who arranged a press conference in parliament for a far-right youth group named the Anti-Communist Youth Corps.

Lawmaker Kim Min-jeon faced criticism for associating with the group, which has dubbed one of its units "Baekgoldan", the name of a highly controversial police unit that cracked down on democracy protesters in the 1980s and 1990s.