Prosecutors are asking the president to order security forces to pursue an arrest warrant against ousted leader Yoon.
Thousands of South Koreans protesting against President Yoon Suk-yeol have held rallies in Seoul, a day after failed to issue a building permit on the suspended leader for his minor declaration of martial law last month.
Protesters gathered outside the presidential palace and along major streets in the South Korean capital on Saturday to demand Yoon's arrest or call for his case to be declared invalid.
The political divide comes as investigators from the corruption investigation office (CIO) of senior officials pressured the country's President Choi Sang-mok to order the presidential security team to pursue a warrant for Yoon's arrest.
On Friday, the presidential security team and the military prevented prosecutors from arresting Yoon during a six-hour standoff inside the presidential palace. Investigators eventually halted construction due to safety concerns.
The fight – which included a scuffle, but no shots were fired – left the warrant shortly after, and the court order is due to expire on Monday.
Yoon's declaration of war on December 3 shocked South Korea and prompted the first arrest warrant to be issued to a sitting president, setting off a new war. a serious political problem.
Yoon is facing charges of treason, one of the few crimes that do not require presidential immunity, meaning he could face prison terms or, at worst, the death penalty.
His lawyers denounced Friday's arrest as “unlawful and illegal” and said they would take legal action.
Also on Saturday, police asked Park Chong-jun, the presidential security chief to protect Yoon, to go for questioning on Tuesday, Yonhap News reported.
Al Jazeera's Patrick Fok, from Seoul, said Saturday's protests had been peaceful and orderly.
“This has been surprising in many ways, but the public's frustration against President Yoon is undoubtedly growing,” he said.
“And you wonder how long these meetings can be peaceful if the situation continues.”
Yoon's aide, Kim Chul-hong, 60, said the arrest of the unopposed president would jeopardize South Korea's security ties with the US and Japan.
“Protecting President Yoon means protecting our country from threats from North Korea,” he told AFP reporters.
Meanwhile, members of the Korea Confederation of Trade Unions, South Korea's largest umbrella union, tried to go to Yoon's house to protest but were stopped by the police.
The organization said two of its members were arrested and several others were injured in clashes with the police on Saturday.
Investigators may make another request to arrest Yoon before the court order expires on Monday. If the permit expires, researchers can apply for another one.
The Constitutional Court said on January 14 to start Yoon's trialwhich would have continued if he had not been present.