Transport Minister Michael Wood has conveyed his expectations over the importance of "responsible and proportionate spending," after his Ministry blew $10,000 on two large red prop 'zeros'.
Newstalk ZB can reveal Waka Kotahi spent $4,885 per number earlier this year.
The props – which glow red and stand about shoulder height on Wood – were part of the agency's Road to Zero campaign.
But National's transport spokesman Simeon Brown said the props were a "ridiculous" waste of money.
"Anyone could make a big red zero for less money than what the Government spent – it could have been made out of polystyrene."
He said it was emblematic of a Government "addicted to spending".
"They don't care that this was money raised by [taxing] motorists, who are paying exorbitant amounts of money through fuel taxes at the pump."
Wood said the $10,000 bill was a very small part of the wider Road to Zero public awareness campaign and the props are being used widely at events, conferences, workshops and trainings across the country.
But his statement to ZB suggests he was not pleased with the bill.
"However, I also believe it is important that all spending Waka Kotahi undertakes as part of this campaign should be responsible and proportionate."
He said the agency should, at all times, consider whether or not spending like this is good value for money.
"My office conveyed my view by email to Waka Kotahi on my behalf after I was advised of the costs of these props."
Questions about the 'zeros' were first raised after Wood and Police Minister Poto Williams posed by one in February, around when the Road to Zero campaign was launched.
Almost $200 million has been earmarked to get New Zealand to try and achieve zero road deaths or serious injuries by 2030.
About $85 million of that has been allocated to advertising activities alone.
Brown has been critical of how much money is being used to promote the policy.
He said that New Zealanders don't need millions of dollars spent on telling them not to die on the road – they want the Government to actually spend the money on making roads safer.
"What our state highway network needs is for its pot-holes to be fixed, it needs better maintenance and for dangerous intersections to be fixed.
"Not the Government telling us what we should be doing on the road and what their policies are."
But Wood says the campaign is aimed at building public awareness and demand for the changes needed to drive deaths and serious injuries down towards zero.
He said the campaign is supporting a much larger Government investment of $2.9 billion in road safety activities over the next three years, including $1.2 billion for road policing.