The chief of security for South Korean President Yoon Suk Yeol said on Sunday he could not cooperate with efforts to arrest the impeached leader, in remarks that could push the political crisis towards another high-stakes confrontation.

With a warrant for Yoon’s arrest on grounds of insurrection set to expire at midnight (1500 GMT) on Monday, the official, Park Chong-jun, cited the legal debate surrounding the warrant as the reason for the lack of cooperation.

“Please refrain from insulting remarks that the presidential security service has been reduced to a private army,” he said in a statement, adding that it had provided security to all presidents for 60 years, regardless of political affiliation.

The comments came after a Seoul court rejected a complaint from Yoon’s lawyers that the arrest warrant was illegal and invalid, the Yonhap news agency said. Telephone calls to the court to seek comment went unanswered.

“Judging the legitimacy of any legal interpretation and execution is difficult,” Seok Dong-hyeon, a lawyer advising Yoon, said on Facebook.

“If there is an error in the legality of law enforcement against the incumbent president, it will be a big problem.”

Yoon became the first incumbent South Korean president to face arrest for his botched attempt to declare martial law on December 3, which triggered political chaos in Asia's fourth-largest economy and a key US ally.

The conservative president was impeached by parliament and is suspended from official duties while the Constitutional Court decides whether to reinstate or remove him.

US Secretary of State Antony Blinken was set to arrive in Seoul on Sunday for talks with senior officials.

On Friday, Yoon’s presidential security service and military troops had blocked criminal investigators from arresting him in a six-hour standoff.

In Sunday’s statement, Park dismissed as “preposterous” an accusation by the main opposition Democratic Party that he had ordered presidential security officers to use live ammunition if they got “caught short” in Friday’s standoff.

Yoon’s lawyers have said the warrant was unconstitutional because the anti-graft force leading his criminal investigation has no authority under South Korean law to investigate any case involving insurrection accusations.

In a statement on Sunday, the lawyers threatened to report to prosecutors Oh Dong-woon, the chief of the Corruption Investigation Office for High-Ranking Officials (CIO) and the investigators for what they called an illegal effort to execute the warrant, in the absence of authority to do so.

The CIO did not immediately respond to a request for comment.

Rallies in Heavy Snow

The dispute over the warrant came against the backdrop of demonstrations by thousands of protesters near Yoon’s official residence amid heavy snow in the capital, Seoul, with some rallies demanding his arrest, and others opposing it.

“We have to re-establish the foundation of our society by punishing the president who has denied the constitution,” said Yang Kyung-soo, leader of the Korean Confederation of Trade Unions (KCTU), a major labour group that joined the protests.

“We must bring down the criminal Yoon Suk Yeol and arrest and detain him as soon as possible.”

Security officials installed barbed wire inside the compound and set up barricades with buses on Saturday, Yonhap said.

Nearby, Yoon supporters held placards reading “We will fight for President Yoon Suk Yeol” and “Stop the Steal”, a phrase popularised by US President-elect Donald Trump’s supporters after he lost the 2020 election.

Some protesters had gathered overnight in downtown Seoul, where temperatures fell below minus 5 degrees Celsius (23 degrees Fahrenheit). More than 6 cm (2.4 inches) of snow has piled up in some areas, prompting a warning.

Similar rallies on Saturday saw police detain two protesters accused of assaulting police officers, Yonhap said.

That day, the CIO again asked acting President Choi Sang-mok, the finance minister, to order the security service to comply with the arrest warrant.

A finance ministry spokesperson declined to comment. In a statement on Sunday the ministry said Choi urged authorities to make sure no one was hurt by efforts to enforce the law.