Prime Minister John Key says he is "not in the slightest concerned" about Labour's calls for an investigation into a donation made to the National Party.
Mr Key said he had not followed the case closely, but he understood there was "nothing untoward" in a $101,000 donation by hotel company owner Earl Hagaman a month before his business was awarded a Government contract.
Political donations were "well and truly disclosed" and Mr Hagaman's Scenic Hotel Group had a long record in the industry, he said.
Mr Key also accused Labour leader Andrew Little of making a "random slur" to get attention during a quiet week in Parliament and said he was developing a reputation for "shooting from the hip".
"Maybe the first thing Andrew Little should do ... is start apologising," Mr Key said.
Scenic Hotel Group founders Earl and Lani Hagaman are considering legal action over Mr Little's claims about the timing of a donation from Mr Hagaman to the National Party a month before the hotel group was awarded a contract in Niue.
The $101,000 donation was made on 18 September, the last week of the election campaign in 2014. A month later Scenic Hotels won a contract to manage the Matavai Hotel on Niue, which is owned by a trust appointed by Foreign Minister Murray McCully on behalf of the Niue Government.
Mr Little said the timing "stinks to high heaven" and wrote to the Auditor General last week asking for an investigation into the donation and the handling of the contract, which was signed between Scenic Hotel Group and the hotel board in October 2014.
The Auditor General is yet to decide whether to investigate but in a statement, the Hagamans said they would welcome an investigation from the Auditor General and would cooperate fully.
"In fact we request that an investigation occurs urgently in order to remove any doubt about the integrity and honesty of our name," said Mrs Hagaman.
Lani Hagaman said the management contract for Matavai Resort Niue was gained by Scenic Hotel Group in an open and contestable process against other hotel groups.
The couple were also considering other legal options to address Mr Little's attack.
"I can assure the public that for us the only thing that will 'stink to the high heavens' will be smell of roses which blossom from the fertiliser Andrew Little likes to spread around to gain his own notoriety."
In a statement, Mr Little said he was pleased the Hagamans would fully cooperate with an investigation. "The public deserves full transparency on this issue given National's largest financial donor gave the party $100,000 during a tender process, then a month later his company was awarded a major government contract. The public must have confidence that the process led by Murray McCully was above board."
Ian Fitzgerald, the chairman of the Matavai Niue Limited which runs the Matavai has also now spoken, saying he would have "absolutely no concerns" if the Auditor-General looked into the process.
Mr Fitzgerald is one of four board members appointed by the Niue Tourism Property Trust to oversee the running of the hotel, which $18 million of New Zealand aid money has been invested in. The agreement was negotiated and signed between Scenic Hotels and the board rather than the Trust itself. Mr Fitzgerald said he was unaware Mr Hagaman had donated to the National Party and the board had only dealt with Scenic Hotels Group's managing director, Brendan Taylor. It was in contract negotiations with Scenic Group for six months before the contract was awarded - well before the donation was made.
Mrs Hagaman said it was a "political beat-up" by Mr Little.
"We are not interested in being Mr Little's political football. These nasty and unfounded allegations need to stop and I would urge Andrew Little to stop wasting tax payer money on trying to promote his own political party and ego."
Mrs Hagaman said in the past the couple had voted for Labour.
"One of the privileges of being a New Zealander is the ability to have freedom of choice and vote or donate to any political party one chooses. In the past both Earl and I have voted Labour but that was when the party had strong morals and direction and did not practice bully tactics on innocent people."
Electoral records show Mrs Hagaman also donated to the Act Party in 2014 and 1998.