South Korean prosecutors charged President Yoon Suk Yeol for his failed attempt last month to place the country under martial law, Yonhap News Agency said, forcing the impeached leader to remain in detention as they build a case against him.

The charges are unprecedented for a South Korean president, and if convicted, Yoon Suk Yeol could face years in prison for his shock martial-law decree, which sought to ban political and parliamentary activity and control the media.

South Korea's impeached President Yoon Suk Yeol has been charged with insurrection after he attempted to declare martial law in December. His ill-fated attempt to impose military rule plunged the country into an unprecedented political crisis and he becomes the first sitting president in South Korean history to be charged with a crime.