Labour Party leader David Shearer says a television interview with Act's John Banks this morning only created more doubt about the discloser of anonymous donations in the Banks' mayoral campaign.
Mr Banks is alleged to have asked internet Tycoon Kim Dotcom to split a mayoral campaign donation into two parts of $25,000 so it could remain anonymous.
The allegations come after police were asked to investigate Mr Banks' listing of a $15,000 donation from SkyCity as anonymous.
Mr Banks denied any wrongdoing when he appeared on TVNZ's Q + A programme this morning and called the allegations a "sideshow".
"I can tell you when I signed my declaration for the mayoralty, I signed it in good faith in the knowledge it was true and correct. I have nothing to fear and nothing to hide and I welcome the inquiry," he said.