There are fewer frontline cops per New Zealander than there were five years ago, and "the people who know it the most are the criminals", says the Police Association.
There was one cop per 503 Kiwis last year, down from one per 488 in 2009, according to police data.
Association president Greg O'Connor said there was a "serious shortage" of frontline staff, and boosting numbers was an obvious fix to reduce recent crime rises.
"I have just visited every district in New Zealand and there is just a serious shortage of frontline response staff and the people who know that the most are the criminals.
"The criminals are the first ones to know when the pressure is off."
His comments came after the latest crime figures showed a national average rise of 3.1 per cent across all crimes in the year to June 30, 2016, with 13 per cent more burglaries, 12 per cent more robberies and 6.5 per cent more assaults.
Labour police spokesman Stuart Nash said more staff were needed to address the hikes and called on Police Minister Judith Collins to seek more funding after the department's budget has gone relatively unchanged since 2009.
"My real concern is that as crime figures increase, we are just not getting the officers on the ground to both prevent and solve the crimes."
In the police's four-year plan to 2020, forecasted staff numbers do not change despite projected population increases to about 4.8 million Kiwis.
"If I was the Minister of Police I would be going to the Finance Minister and saying we need more money," said Nash.
Collins maintains that police have enough resources, there are more officers under National and targeted operations are tackling issues.
She said police received "considerable extra funding" from the government, referring to a 2.8 per cent increase in this year's budget and 600 new positions created between 2009 and 2011.
Recent crime increases were short term and being addressed with specialist operations, particularly around burglary, and the ratios were worse under Labour, she said.
A police spokesperson said the department was "focussed on working more effectively and efficiently within our existing resources and on making other efficiencies where we can".
O'Connor said increasing staff numbers would make more of an impact now than ever as staff were so efficient in using resources.
"Science the world over shows that if you increase police staff you will catch more criminals. Police have got very, very good now at utilising the staff they have got, so an increase in staff numbers would make more difference now than ever."