A provincial governor in South Korea, widely seen as the leading presidential hopeful for the next election, resigned on Tuesday after a woman aide accused him of raping her four times over the last year. In a Facebook post, Ahn Hee-jung apologised to the woman for his “foolish behaviour” and announced his retirement from public life.

The 52-year-old was the governor of South Chungcheong province. His office had initially denied the allegations by one of his secretaries, but he retracted the statement on Tuesday and apologised. Police have started an investigation, according to Yonhap news agency.

“It’s all my fault,” Ahn said in his Facebook post. “I want to tell her [the secretary] that I am really sorry.”

In an interview to a local TV channel on Monday, the secretary had said she knew there were other victims too, and she hoped her interview would encourage them to speak out too. Her interview follows a series of other allegations of sexual harassment against men in power in South Korea.

Ahn was a major contender for president in the 2017 presidential elections as well, which his party colleague Moon Jae-in won.