"The number of general duties constables now stands at 2593 this year, a drop of almost 18 per cent since 2009."
He said it was "a terrible indictment of a Government that talked the talk on police numbers but had allowed the number of constables handling crime and complaints to fall year after year".
"In Northland alone, the number of general duties constables has tumbled from 140 in 2009 to just 113."
Across the country, high-volume crimes such as burglaries had a very low resolution rate, he said.
"Despite this, funding for the police in the Budget was reduced by a whopping $15.3 million.
"Police say they want a higher presence in New Zealand communities, yet there is no money or staff to increase foot patrols."
Police Minister Michael Woodhouse said Mr Davis was "either being tricky or is utterly confused".
"Either way, his comments are untrue."
Mr Woodhouse said both frontline and overall police numbers have increased under the National-led Government.
"Our communities are safer as a result," he said.
"There are now more police on the beat, and more foot patrols, than ever before."
Mr Woodhouse added that Budget 2015 included more than $1.5 billion to continue support and invest in police.