Police investigating the Sungnyemun fire will request an arrest warrant Wednesday for the man who confessed to the crime the previous day.

They planned to make the request late Tuesday but were delayed by further probing of the 69-year-old man, identified only by his surname Chae.

Police said they've confirmed that Chae acted alone when he climbed a ladder to enter the 600-year-old wall gate at 8:45 p.m. Sunday.

Chae confessed that he sprinkled thinner inside the two-story wooden structure and used a disposable lighter to start the fire, escaping by taxi immediately after.