South Korean prosecutors started investigating domestic conglomerates Lotte Group and SK Group as part of a wider probe into a graft scandal that led to Park Geun-hye’s removal from the presidency, Yonhap news agency reported on Wednesday.

Yonhap, citing unidentified sources, said the prosecution suspected improper dealings between Park and the two conglomerates. A spokesman for the SK Group told Reuters the conglomerate would cooperate with the investigation.

Lotte Group could not be immediately reached for comment.

Park has denied wrongdoing.

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