Police will be out in force, and subway stations and at least one school will be closed over safety concerns when South Korea's Constitutional Court rules whether to oust or reinstate impeached President Yoon Suk Yeol.

South Korean President Yoon Suk Yeol, who lawmakers voted to impeach and was indicted on criminal charges for declaring martial law last December, was cleared to be released from detention on Friday.

Police in South Korea are prepared to mobilize "all available equipment" to prevent unrest when a court announces whether it upholds the impeachment of suspended President Yoon Suk Yeol, Seoul's police chief said on Monday.