An Upper House panel has questioned a senior executive of a defense-related group in the scandal involving Yamada Corp., a defense equipment trading house. Mr. Naoki Akiyama, executive director of the Japan-U.S. Center for Peace and Cultural Exchange, gave unsworn testimony to the panel Tuesday.

Meanwhile, public prosecutors on the same day filed an additional bribery indictment against former Vice Defense Minister Takemasa Moriya; Mr. Motonobu Miyazaki, a former executive of Yamada Corp. and founder of Nihon Mirise Corp., another defense equipment trading firm; and Mr. Osamu Akiyama, a former president of Yamada's U.S. subsidiary.

Mr. Naoki Akiyama's group includes politicians with influence on defense policy and officials of defense-related companies. He denied suspicions raised by Diet members, but public prosecutors have already searched his group's office and confiscated material. It is hoped that they will push for a probe to determine whether illegal activities took place in and around the group.