The National Party is claiming Winston Peters called Deputy Police Commissioner Wally Haumaha to assure him "things would be okay" after an inquiry was launched into the process of his appointment.
MP Chris Bishop used his Parliamentary privilege to claim links between NZ First and Mr Hauhama "go further" than his unsuccessful bid for NZ First candidacy in 2005.
"Winston Peters rang Wally Haumaha, after the inquiry into his appointment was announced. He gave him assurances, or words to that effect, that things would be okay.
"That is deeply, wildly inappropriate," Mr Bishop said.
Acting Prime Minister Winston Peters denies the claim.
In a statement Mr Peters says: "During Parliament’s General Debate this afternoon the National Party MP Chris Bishop claimed to have made a revelation related to the Haumaha inquiry. He hasn’t made a revelation and I’m swatting-off this midge right now.
"There is no basis to Mr Bishop’s claim that I rang Mr Haumaha after the inquiry into his appointment was announced, nor have provided any assurances on the matter. I have not called nor had any reason to call Mr Haumaha since the controversy.
"My office has checked all my phone records since the inquiry was announced. No such call was made.
"It is a matter of public record that this inquiry was initiated in my capacity as acting Prime Minister.
"The public can have faith in the inquiry. It was initiated by Cabinet, it is being conducted by a highly respected independent QC, and it will report back to Cabinet. The terms of reference have been publicly released. The final report will be made public.
"Regardless, any suggestion that New Zealand First Ministers are seeking to unduly influence this inquiry is baseless nonsense," says Mr Peters.
There is currently an inquiry underway into the processes of the appointment of Wally Haumaha as Deputy Police Commissioner after comments he made defending police officers accused of rape in 2004 came to light.
Mr Haumaha has since apologised for the comments, saying they do not reflect his views.
There have also been accusations of bullying behaviour on a project Mr Haumaha was working on involving two women from the Justice Ministry and one from Corrections.
The incident reportedly led to the policy analysts walking out of Police National Headquarters and completing the project from their own respective offices.