OSAKA -- Former high-ranking officials of the Public Management, Home Affairs, Posts and Telecommunications Ministry pleaded guilty Monday to charges of violating the Public Offices Election Law to help their former boss win election to the House of Councilors in July.

Tsuyoshi Mishima, 59, former chief of the ministry's Kinki Regional Bureau, and Tetsuhiko Nishida, 55, a former head of the Kinki bureau's general affairs department, said at the opening of their trial at the Osaka District Court that the charges brought against them were valid.

Mishima and Nishida are charged with using their positions as public servants in violation of the elections law to assist Kenji Koso's campaign in the Upper House election.

Although Kozo won a seat in the Diet, he later resigned under pressure.