National says the Police Minister needs to front up over whether police paid to have firearms that were stolen from the Palmerston North station returned.
Eleven guns, including some handed in as part of the amnesty on now illegal firearms, were taken from the station, after a back door was left open.
Police spokesperson Chris Bishop said he understands some, if not all, of the retreived firearms were bought back by police.
"The Minister needs to be honest about what has happened here.
"It would be deeply embarrassing for the government's gun buyback scheme to start by paying criminals for weapons stolen from a police station," he said.
The 11 guns were stolen from the Palmerston North police station on Anzac Day, when a thief walked through a door that had been left open.
The firearms were a range of weapons being held as exhibits, or handed in for destruction, including one semi-automatic.
This embarrassing burglary prompted Police Commissioner Mike Bush to order a review into the security around firearms at police stations.
Police wouldn't confirm or deny whether they had paid to have the guns returned.
In a statement Central District Police said they were very focussed on recovering the three outstanding firearms, but they would not discuss specific matters relating to the ongoing investigation.
Police Minister Stuart Nash said the police methods for getting these guns back were not his concern.
"There is a constitutional convention that the Minister of Police does not become involved in the organisational matters of the New Zealand Police", he said.
Mr Nash said he was briefed by police when the guns were stolen, but everything since then had been operational.
"As far as I was concerned that was the end of the matter, how police got those firearms back is then up to them.
"I have no idea, and you know what, I really don't want to know.
"I trust New Zealand police to do the best job possible to ensure they solve this case," he said.
But Mr Bishop said the Minister's stance was a dereliction of his duty.
"He is the person politically accountable and there is high public interest in the buy-back scheme, and a high public interest in the theft of these weapons from Palmerston North police station in the first place.
"He has a duty to the public and to the Parliament to be upfront about what's happened here and explain," Mr Bishop said.
But Mr Nash said those are two completely different issues.
He said one was about taking guns that were now illegal out of the community, and the other was about solving a burglary.