President Yoon Suk Yeol declares martial law during an emergency address at the presidential office in this photo provided by the Presidential Office, Seoul, Dec. 3. Yonhap

Police said Monday they are reviewing whether to impose a travel ban on President Yoon Suk Yeol to investigate him over treason and other charges related to his short-lived declaration of martial law last week.

Yoon has been booked as a suspect in investigations by both the police and the prosecution into charges of treason, mutiny and abuse of power raised against the president and multiple senior government and military officials involved in martial law operations last Tuesday.

"Securing the necessary materials comes first," a police official said during a press briefing when asked why Yoon has not been placed under a travel ban. "We are deciding based on a comprehensive review, including the possibility he will leave the country."

When asked about the possibility of arresting Yoon without a warrant, the official said it would be possible if the requirements are met.

Police also did not rule out questioning Yoon in person.

"There are no human or physical restrictions to the subject of an investigation," Woo Jong-soo, chief of the National Office of Investigation at the National Police Agency, said during the briefing.

The police have launched a special team of some 150 investigators to handle the case.

The Corruption Investigation Office for High-ranking Officials (CIO) has asked the police and the prosecution to transfer the case to the CIO, citing questions about "fairness" stemming from their relationships with the subjects of the investigation. (Yonhap)