Prime Minister John Key won't be drawn on whether he supports a move by police to stop prosecuting some small-time P dealers.

Officers in the Waitemata policing district are no longer prosecuting some low-level dealers of pure methamphetamine, or P - such as those who sell to a neighbour.

Speaking to Radio New Zealand, Detective Senior Sergeant Stan Brown said arresting low level offenders did not work by itself and it could be better in some cases to refer people for rehabilitation.

Key has led the Government's "War on P", which has involved a range of measures to target drug manufacturers, gangs and addicts.

He knew little about Waitemata Police's approach, so he did not want "to overly critique it".


But he said the Government had generally tried to emphasise prosecution of P dealers rather than those who used them.

"We prosecute both, obviously," he told reporters at his weekly press conference. But most of the Government's energy went into cutting off the source of the drug.

Key said the National-led Government's policies had worked "on one level". The number of people using the drug had fallen from 2.2 per cent to 1.1 percent of the adult population since new measures were introduced in 2009.

The remaining 1.1 per cent were "more intense", frequent users of the drug, Key said, and could benefit from a less punitive approach.

"Rehabilitation is certainly a way of working through that," he said.

Key said it was important to get the balance right in drug policy because P "destroys lives".

Radio New Zealand reported that serious dealers and people who sold P to children were still being prosecuted in the Waitemata policing district. Decisions about prosecuting low-level offenders was made on a case by case basis, Brown said.