Police Commissioner Mike Bush has promised to look into the reasons behind a "small rise" in crime - as Labour points to a lack of police officers.
Police Minister Judith Collins said population increase, more reporting of crime and criminals deported from Australia are possible reasons for the preliminary figures.
Statistics released by police show that in May and compared to last year there were increases in eight out of ten offences - including assaults, burglary, disorder and drug use.
The crime stats were a focus of opposition MPs when Mr Bush fronted a Parliamentary select committee today with Police Minister Judith Collins.
Labour's Phil Goff - who is campaigning for Auckland mayor - said in the past five years Auckland's population had increased by about 160,000, but figures showed there had been only five new police constables.
"Is that sufficient to match the increase in population, but also the increase we've seen in the last couple of years in burglary statistics, and the increase in your statistics yesterday that show crime across Auckland is increasing in just about every category across the board from where it was a year ago," he asked.
Mr Bush said that population increase didn't always equal an increase in crime. That was shown by the 10-year trend of falling crime in New Zealand.
Mobile technology was helping frontline officers spend more time to fight crime, he said.
"Yes, I am conscious of the recent small rise. And we will address that. But it's not just about the numbers, it's about how effective and how productive our people are."
Speaking after the meeting, Ms Collins said the May crime figures were yet to be verified and weren't official.
"There may have been a slight bump in crime...but I think that what we are seeing is if police go after drug offenders, that's always going to be counted as offences. If they don't do that, then that will drop down the crime statistics.
"We do have more people in the country, we've got these people who have been sent back from Australia because of their criminal activity...and people have far more confidence too in reporting domestic violence to police."
Labour's police spokesman Stuart Nash said police could not continue to be asked to do more with less.
"This is a real concern considering the police's own strategic plan from 2016 to 2020 states that there will be no increase in police numbers for the next five years."
May crime statistics
(Nationally, and compared to May 2015)
• Drugs supply: 558 (573)
&bull Drugs use: 1223 (1090)
&bull Disorder: 1919 (1788)
&bull Assaults police: 151 (132)
&bull Serious assaults resulting in injury: 992 (878)
&bull Public place assaults: 947 (748)
&bull Dwelling assaults: 2724 (2254)
&bull Robbery: 198 (147)
&bull Burglary: 6071 (4649)
&bull Vehicles stolen: 2000 (2012)
Source: Police monthly statistical indicators, May release.