Seoul, Jan 11 (IANS): The former head of South Korea's Presidential Security Service (PSS) appeared before police on Saturday for questioning over allegations that he blocked investigators' attempt to detain impeached President Yoon Suk Yeol over a martial law probe.

Park Chong-jun, who stepped down as chief of the PSS the previous day, has been booked on charges of obstructing official duties as presidential security officials have blocked the Corruption Investigation Office for High-ranking Officials (CIO) from executing a warrant to detain Yoon.

Park appeared at the Joint Investigation Headquarters in western Seoul at around 9 a.m. for the second day of questioning following his initial appearance on Friday.

On Friday, Park submitted his resignation shortly before appearing for 13 hours of police questioning, following two prior refusals to comply with the police requests.

The CIO secured a new arrest warrant for Yoon on Tuesday after an initial seven-day warrant expired and is coordinating with police on the second attempt to arrest Yoon.

Meanwhile, PSS Deputy Chief Kim Seong-hoon, the current acting head of the service, snubbed the police's request to appear for questioning for the third time on Saturday, saying the seriousness of his duties in protecting Yoon makes it impossible for him to step away from his post even for a brief moment.

Kim is expected to lead efforts to stop the execution of the second arrest warrant as Park has resigned, Yonhap news agency reported.

Police are also likely to seek an arrest warrant against Kim as he has ignored three summonses.

Earlier in the day, US National Security Advisor (NSA) Jake Sullivan had portrayed impeached President Yoon Suk Yeol's botched martial law bid as "shocking" and "wrong," but voiced confidence that "structurally," the South Korea-US alliance was "incredibly healthy."

Speaking in a press meeting on Friday, he also noted that the Biden administration had not been able to make "substantial" progress in efforts toward the denuclearisation of the Korean Peninsula, with the security trend moving in the "wrong" direction. However, he stressed that America and its allies were in a "materially better" position to deter North Korean threats.

He had also expressed concerns over the "risk" of North Korea using the ongoing political turmoil in South Korea to engage in provocative activities but underscored that Pyongyang "should make no mistake" given the strength of the bilateral alliance.

"I think the declaration of martial law in early December was shocking. I think it was wrong, and now we are watching a constitutional procedure play out. We want to make sure that it does so without violence, that it does so in accordance with the ROK Constitution," Sullivan had said, using the acronym for South Korea's official name, the Republic of Korea.

South Korea had been thrust into a period of political uncertainty following Yoon's short-lived martial law declaration on December 3, 2024, and his subsequent impeachment on December 14, 2024.