The leader of the Unification Church, Han Hak-ja, appeared for questioning by prosecutors on Wednesday over alleged involvement in bribing the wife of ousted South Korean President Yoon Suk Yeol as part of a criminal probe into the former first couple.

Han declined to answer questions from reporters about the allegations as she arrived at the office of the special prosecutor.

"I've been unwell," she said, when asked why she had chosen to respond to questioning, after refusing earlier summons.