While police numbers in the South slowly increase, gangs and methamphetamine are infiltrating the lower South Island at an unprecedented rate, Mr Cadogan says.
Ten of 88 extra police officers promised for the Southern district over the next five years have arrived so far, six months into a new recruitment drive.
But Mr Cadogan says many more are needed, especially in small at-risk towns.
He did not want to specify any particular towns, but said some were experiencing levels of gang infiltration never seen before.
It was a concern that other areas were getting many more new officers per head of population compared with the South’s allocation, he said.
In response to Mr Cadogan’s call for more police, Southern District Commander Superintendent Paul Basham said police were committed to reducing meth-related harm.
"We are in the process of adding one more officer in Balclutha."
There would be further growth in rural policing and investigating in the South over the next five years, Supt Basham said. Mr Cadogan acknowledged crime rates had traditionally meant the North Island needed more police than the South.
However, the growing presence and sophistication of gangs in the lower South Island, coupled with the spread of methamphetamine, meant Southern police urgently needed more staff and resources.
"They’re most certainly infiltrating all across the lower South Island.
"I believe that if we allow it to develop ... there will be towns that will rapidly change and you’ll never ever get them back again."
In his view, the solution was simple.
"We need more police on the ground across the lower South Island.
"The level of sophistication [of criminals] has risen dramatically in the last three years and there needs to be an acknowledgement of that from Wellington."
Mr Cadogan said southerners needed to "wake up" and realise the degree to which police were losing ground to criminals in the South.
"Anyone who has any gang association, they don’t fear the police."
He said it was not good enough that the number of new police headed to the North Island over the next five years was significantly higher than those headed South.
Of the 1800 extra police officers promised by 2023, the equivalent of 2.7 per 10,000 head of population are tagged for the North Island, compared with 2.3 for the South Island.
The Southern district’s target of 88 new officers represents a growth of 2.7 additional police per 10,000 people, compared with 5.3 in the Eastern district (East Cape through to southern Hawkes Bay), five in Northland, 3.3 in Waikato, 2.9 in Tasman and two in Canterbury.
That represents a 16% increase in the number of sworn officers in the Southern district (Otago and Southland), as against 27% in Eastern and 25% in Northland.
As well, figures released under the Official Information Act show of the 14 wings of new police graduating in 2018-19, just 60 officers are headed to Southern, versus 91 to Canterbury, 96 to Waitemata and 166 to Counties Manukau.
A police spokeswoman said between June 2017 and October 2018, the Southern district police constabulary had grown by 10.
The Southern district was on track to add the promised 88 officers by the end of 2023, she said.
Extra officers
• 88 extra officers headed to the Southern district (Otago and Southland) by end of 2023 (on top of October 2017 staffing levels).
• 1800 new officers promised nationally over the same period.
• 10 additional sworn staff on top of existing levels have arrived in Southern between June 2017 and October 2018.
• 2.7 more police per 10,000 people coming to Southern district, about half as many per head of population as are headed to the Northland and Eastern districts.
• About 560 sworn staff in Southern district.
