Sugimori abruptly resigned in August citing personal reasons although the oil and metals company had booked strong first quarter results.

Public broadcaster NHK on Wednesday cited Eneos as saying that Sugimori had sexually harassed a woman in July.

Without claiming the harassment was sexual in nature, Eneos, Japan's biggest oil refiner, said in its statement that it investigated allegations made against Sugimori and concluded that he had "engaged in inappropriate behaviour" and asked him to resign.

(Reporting by Sakura Murakami; Editing by Christian Schmollinger)