Thousands of rival South Korean protesters have rallied in the capital a day after a failed attempt to arrest the country’s suspended president, Yoon Suk Yeol, for imposing a short-lived martial law decree that led to his impeachment.

The country has been plunged into political chaos since last month, with Yoon defiantly holed up in the presidential residence surrounded by hundreds of loyal security officers who have so far resisted efforts by prosecutors to arrest him.

Thousands of protesters for and against Yoon gathered in front of the residence and along major roads in Seoul on Saturday, either demanding his arrest or calling for his impeachment to be declared invalid.

Kim Chul-hong, 60, a supporter of Yoon, said arresting him could undermine South Korea’s security alliance with the US and Japan.

“Protecting President Yoon means safeguarding our country’s security against threats from North Korea,” he said.

Members of the Korean Confederation of Trade Unions, South Korea’s largest umbrella union, attempted to march to Yoon’s residence to demonstrate against him, but were blocked by police.

It said two of its members were arrested and several others were injured in clashes.

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 the warrant is carried out, Yoon will become the first sitting South Korean president to be arrested.

Investigators have asked the finance minister, Choi Sang-mok, who was installed as acting president a week ago, to back the warrant by ordering the presidential security service to cooperate.

The service said two of its top officials had refused a police request for questioning, citing the “serious nature” of protecting Yoon.

In scenes of high drama on Friday, Yoon’s guards and military personnel shielded him from investigators who eventually called off the arrest attempt, citing safety concerns.

The showdown, which reportedly included shoving but no shots being fired, left the warrant in limbo, with the court order due to expire on Monday.

The Corruption Investigation Office for High-Ranking Officials (CIO) could make another attempt to arrest him before then. If the warrant lapses, they may apply for another.

The constitutional court has scheduled the start of Yoon’s impeachment trial for 14 January, which will take place in his absence if he does not attend.

The former presidents Roh Moo-hyun and Park Geun-hye did not appear in court during their impeachment proceedings.

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 making another attempt to arrest the suspended president.

Chae Jin-won, of Humanitas College at Kyung Hee University, said: “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.”

Yoon told his rightwing supporters this week he would fight “to the very end” for his political survival.

South Korea’s key security ally, the US, called for political leaders to work towards a “stable path” forward.

The outgoing US secretary of state, Antony Blinken, is scheduled to hold talks in Seoul on Monday, with one eye on US-South Korea relations and another on nuclear-armed North Korea.