A South Korean court on Friday rejected former President Yoon Suk Yeol’s petition for release, upholding his detention over allegations he tried to impose martial law in December, Yonhap News reported.

Yoon appeared at Seoul Central District Court for a closed-door hearing earlier in the day, before the court denied his request. He had filed the petition Wednesday seeking a judicial review of his arrest, nearly a week after he was detained on charges tied to his alleged Dec. 3 martial law plot.

On Thursday, Yoon refused to attend his insurrection trial for the second time, saying he would boycott all future proceedings unless special counsel Cho Eun-suk and her team are removed from the case.

Yoon’s lawyers argue the criminal charges cannot be substantiated and that he poses no risk of destroying evidence. They also claim the five charges listed in his arrest warrant -- including violating the rights of Cabinet members and creating a false martial law document -- are already covered under the main insurrection charge for which he is currently standing trial.

Yoon remains in custody at the Seoul Detention Center under a court-issued arrest warrant last week.