Frustration over the conduct of senior members of the Liberal Democratic Party faction once led by former Prime Minister Shinzo Abe erupted Thursday, as three faction members gave rare testimony before an Upper House political ethics committee.

Former Upper House LDP Secretary-General Hiroshige Seko, former Olympics minister Seiko Hashimoto and Upper House lawmaker Shoji Nishida all reiterated that they were not involved in an unlawful slush funds scheme at the center of a recent investigation.

In his testimony, Nishida — who wasn't part of the faction's leadership — expressed strong irritation over the inability of Seko and other senior leaders to uncover details about the decision that instigated the practice of kickbacks.