Winston Peters has rejected Paula Bennett's claim in Parliament that the previous National-led Government halved meth use while in power.
"That claim is the world's best kept secret," Peters, the Deputy Prime Minister, told Bennett. "If the meth trade was defeated, why on earth would we devote so much time and so much money to get on top of it?"
Bennett, National's Drug spokesperson, asked why the Government cancelled National's Meth Action Plan - announced by former PM John Key in 2009 - which set $10 million aside each year from proceeds made up of seized criminal money.
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According to a Cabinet paper shown to Stuff, the Government cancelled the programme as it is considered a "broader-based approach to crime-related harm was needed".
Bennett claimed the programme "did in fact work" and said it "did halve the rate of adult meth use as it was 2.1 percent in 2009 and halved to 0.9 percent in 2015", pointing to a 2015 report.
The "2.1 percent" Bennett referred to was actually 2.2 percent - a figure from the 2007/08 New Zealand Alcohol and Drug Survey which reflected the total population from years 16-64.
Peters, standing in for the Prime Minister, said Bennett was "simply not correct" and said that was "why we are seeking alternative measures, including having the frontline police power to do the job".
Police Commissioner Mike Bush announced in September that 500 police would be dedicated - in an "unprecedented" move - to preventing and combating organised crime in New Zealand.
"If the meth trade was defeated, why on earth would we devote so much time and so much money to get on top of it?" Peters asked Bennett. "That is what the community has advised us to do."
Peters then pointed to the country's biggest ever meth bust in December last year off the coast of 90 Mile Beach in Northland, where dealers were caught importing almost 500kg of the drug.
Peters asked Bennett: "If the meth trade was being successfully attacked by the previous administration, how come 500kg appeared on 90 Mile Beach?
"I invite that member to reflect on the 90 Mile Beach [meth bust] and other events where nothing was happening, against what is being done now by the Government and police, in particular."
Meth convictions have been increasing across the country compared to dropping cannabis convictions, a report earlier this year found.
Low-level cannabis convictions fell "dramatically" between 2009 and 2015, while methamphetamine convictions have risen since 2014.