A ruling People Power Party lawmaker resigned as chief of staff to party Chairman Lee Jun-seok on Thursday ahead of an ethics committee meeting the party plans to hold over allegations Lee received sexual services as a bribe about 10 years ago and attempted to cover it up.

In a text message to the press, Rep. Park Seong-min said he quit for unspecified personal reasons, but the resignation came a week before the PPP's ethics committee holds a meeting to determine whether and how to discipline Lee over the sexual bribery allegations.

"It seems I do not have any more roles to play (for Lee)," Park told Yonhap News Agency later. "I don't think I can be of help."

Any punishment stronger than a warning could imperil Lee's political career a year after he took over the chairmanship and would push the PPP to elect a new leader. Lee has been claiming he is innocent, saying the claims against him are false.

Since Park has been considered a "bridge" between President Yoon Suk-yeol and Lee, his decision sparks speculation that Yoon could be turning his back on Lee over the sexual bribery case.

The resignation could drive Lee into a corner amid a power struggle over the party leadership between Lee and a pro-Yoon faction of lawmakers in the PPP.

Lee, whose term ends next year, recently launched a reform committee, a move aimed at gaining firm control of the PPP against pro-Yoon lawmakers. (Yonhap)