Seoul, Jan 20 (IANS): South Korean Police on Monday made another unsuccessful attempt to search the Presidential Security Service (PSS) and a presidential safe house as part of their investigation into President Yoon Suk Yeol's failed martial law bid.

At around 1:30 p.m., investigators arrived at the presidential office in the central Seoul district of Yongsan, where the PSS is located, and the safe house in the Samcheong-dong neighbourhood to try to secure surveillance camera footage.

The safe house is where Yoon met with the national and Seoul police chiefs to discuss his martial law plans three hours before he announced the decree on December 3.

Investigators sought to obtain surveillance camera footage from the safe house, with the server stored at the PSS office, to identify the people who entered the premises before and after Yoon's declaration of martial law and what instructions they received.

However, they had to leave the premises slightly after 5 p.m. as the PSS denied access, citing laws requiring the consent of responsible authorities for searches of locations involving military secrets or classified government data, Yonhap news agency reported.

The raid comes a day after Yoon was placed under formal arrest on charges of leading an insurrection and abuse of power and as senior PSS officials have either resigned or are under investigation in connection with the case.

Previous attempts to search the locations largely failed due to resistance from the PSS.

Earlier in the day, Yoon Suk Yeol was moved to a solitary cell in the Seoul Detention Center's general wing after being formally arrested over the weekend, a correctional official said.

Yoon was transferred to a 12-square-metre cell at the detention center in Uiwang, south of Seoul, on Sunday after the Seoul Western District Court issued a warrant for his formal arrest, according to Shin Yong-hae, commissioner general of the Korea Correctional Service.