Volunteer Charlie Kirchheimer (25) displays jars of dried cannabis buds at the La Brea Collective medical marijuana dispensary in Los Angeles. Photo: Reuters

The Cannabis Party's plans to offer exclusive tours to California to buy legal cannabis have been thwarted by Ministry of Health advice.

The ministry and Customs today released new information to travellers entering New Zealand from the United States with medical cannabis products.

``Cannabis-based products supplied in the United States of America cannot be carried with you when entering or leaving New Zealand,'' the ministry said.

``A number of US states permit the medical use of cannabis. However, cannabis-based products for medical use from the United States are not considered lawfully supplied under federal law, unless the product has US Food and Drug Administration approval.

``To date, no drug product containing or derived from botanical cannabis (the cannabis plant) has been approved by the Food and Drug Administration. ''

Prior to the ministry's update, the Cannabis Party claimed it had found a loophole in the misuse of Drugs Act.

``A loophole in the misuse of Drugs Act allow medical cannabis to be brought into New Zealand if it was legally obtained abroad for the treatment of a medical condition,'' the party's website reads.

The party last week announced its exclusive guided tours of California to buy legal cannabis.

Mt Roskill byelection candidate Brandon Stronge said the tour ``was a unique opportunity for medical cannabis users to bring cannabis back into New Zealand legally''.

A doctor's evaluation and medical cannabis recommendation were advertised as part of the package, costing some $5000.

Ministry of Health spokeswoman Charlotte Gendall said the updated rules had not been put in place in light of the Cannabis Party's California Tour plans.

``No. It's part of ongoing progress about keeping the public well informed. It's not as a result of any outside influence.''

Ms Gendall added that if the Cannabis Party attributed the new update in rules as a response to their California plans, that would be ``untrue''.

The Cannabis Party has been approached for comment.