Japanese Defense Minister Tomomi Inada resigned on Friday amid an alleged cover-up of internal documents, including the daily activities and safety conditions of Japan's Ground Self-Defense Force during its United Nations peacekeeping operations in South Sudan.

Accepting Inada's resignation, Prime Minister Shinzo Abe apologized on Friday to the public. Abe said Foreign Minister Fumio Kishida would add the defense portfolio to his duties until a new defense chief is appointed.

At ad hoc meetings of Japan's parliament on Monday and Tuesday, Abe turned down opposition lawmakers' demand to fire Inada.