Prime Minister Taro Aso was forced to defend his family firm's alleged wartime deeds Thursday, as the revisionist essay by ousted Air Self-Defense Force chief Gen. Toshio Tamogami continued to cause a political stir.

Aso Mining Co. allegedly used thousands of Koreans and Chinese, Australian, British and Dutch prisoners of war as forced laborers during World War II.

"No facts have been confirmed," the prime minister told the Upper House Committee on Foreign Affairs and Defense when asked whether Aso Mining used Allied POWs as forced labor during the war.