Customs has updated its guidelines around cannabis-based products, just a week after a loophole was identified in the law.

Under direction from the Ministry of Health, it's banning all medicinal cannabis products from being carried in on flights from the United States.

LISTEN: Brandon Stronge: Loophole to bring cannabis into NZ legally

The Ministry said this has nothing to do with tours organised by the Cannabis Party.

But just last week, the Cannabis Party's Mt Roskill candidate Brandon Stronge announced he's organising guided tours of California to buy these legal products.

He said they can legally be brought back to New Zealand, under a doctor's recommendation in the United States.

Stronge is describing this latest move as interesting timing by the Ministry.

"It's really unfortunate that they've gone and blocked this loophole from the US, but they haven't blocked it for other legal countries like Canada."

Stronge is not sure that what Customs and the Ministry of Health has done in singling out and banning one product is allowed under the law.

"How can they unfairly say that cannabis is not a medication, but every other therapeutic medication is okay?"