Prime Minister John Key denies that the fight against methamphetamine is being lost but says importations are up from countries where the drug is cheap because of the big profits to be made by gangs.
He told reporters in London on Monday that the government's methamphetamine action plan initiated between 2008-11 had led to a reduction in the drug's use.
"What has changed is there is a lot less of the domestic manufacture because it's so much harder to buy the precursor, pseudoephedrine, over the counter."
But Mr Key said that had led to greater efforts to import the product, with big drug seizures now being reported.
"What's partly driving these very big seizures ... is that the street price in a place like Mexico is a fraction of what it is in New Zealand."
That was a big incentive for gangs to get involved in importation, Mr Key said.
"In one sense we're still doing OK in terms of trying to control it but we've got a bigger target on our heads now because there's just so much money involved with these gangs, that's our challenge."
Mr Key said the government was "effectively refreshing the methamphetamine action plan", going back to take a closer look at the importation of the drug to see if police and customs have all the resources they need.