Questions have been raised over another donation to the defunct mayoral campaign of Act New Zealand leader John Banks, which was listed as anonymous yet was made out for a specific amount and purpose.
The donation records from Mr Banks' 2010 campaign for the Auckland mayoralty list $15,690 being donated for radio advertising.
It has led to questions over how a donor would find out how to give the right amount of money to cover a specific bill and still remain anonymous.
Labour's Trevor Mallard said Mr Banks should explain how an unknown donor managed to find out exactly how much money needed to be donated to cover radio advertising costs.
He said an alternative was the donation was "in kind" - meaning the cost of the advertising had been donated by the company which had done the work.
Mr Mallard said the advertisements also had to be properly authorised before running. He said this would also raise awareness inside the campaign camp.
"It seems to me it can't be listed as anonymous."
The Weekend Herald has seen the expenses sheet filled in by Mr Banks which showed The Radio Bureau had done work worth $15,690.
The expense is described as being for the "last three days election advertising schedule".
The Radio Bureau, a specialist advertising agency for radio run by The Radio Network andMediaWorks NZ, has not responded to calls.
Chief executive Gil Stewart said on Thursday: "I can't comment at this time." She did not reply to further messages.
Prime Minister John Key said yesterday he had not sought any further assurances from Mr Banks.
"He has given me a cast-iron assurance he has complied with the local electoral law.
"As I have said all week, I'm not going to sack a minister for complying with the law."
Mr Key also brushed off questions about one of his MPs, Scott Simpson, who emerged listed as a "fundraiser" for Mr Banks' campaign. He said he had not spoken to Mr Simpson and saw no need to.
Veteran activist Penny Bright yesterday complained to the Serious Fraud Office over the issue. She then headed to the heart of Mr Banks' Epsom electorate to begin what she called "her by-election campaign".
Detectives are expected to visit Dotcom in Coatesville, north of Auckland, where he waits on bail for an extradition hearing brought by the United States in connection with his now defunct internet file-sharing business MegaUpload.
They will seek to question him, his wife Mona, and any staff over their connection to the donation scandal which has enveloped Mr Banks.
Mr Dotcom has said Mr Banks asked for money for his 2010 election campaign and was offered $50,000. He said the payment was divided at Mr Banks' request to disguise its origins.
The $25,000 payments are listed among three others on Mr Banks' donation return.
The donation is one of three being investigated by police. The others are the "radio advertising" donation and a $15,000 contribution from SkyCity casino.
Mr Banks, who also lobbied for Dotcom and provided feedback, has denied any wrongdoing and said he followed the law.
When Mr Banks flew to Wellington on Tuesday to attend Parliament, it was with one opponent, NZ First leader Winston Peters, seated at his side.
On the return trip last night, Mr Banks found himself confronted by not one foe - but two.
On boarding the plane, it turned out his seat was directly across the aisle from Labour's Trevor Mallard. There was no escape - Mr Peters was sitting in the row behind.
Mr Mallard said: "As soon as he saw me, the headphones went on and the head went down. Lots of people around were laughing about it."
