Police raid properties in Papamoa, Mount Maunganui and West Auckland

Police and fisheries officers in Birch St, Tauranga during a raid that took place across the city this morning.Photo / Alan Gibson

Police are raiding homes and businesses across Tauranga and Auckland following an investigation into synthetic cannabis and money laundering.

Search warrants have been executed in Papamoa, Mt Maunganui and west Auckland, as well as a lunch bar and tyre shop in the Birch Ave industrial area. Officers were also seen visiting a rural property in Pyes Pa.

Assistant Commissioner Richard Chambers, in charge of investigations, said the alleged synthetic cannabis supply ring was targeted because of the harm the drug causes in the community.

Assets allegedly purchased with the profits of the synthetic cannabis were also being restrained today, he said.

Police and fisheries officers took part in the raid. Photo / Alan Gibson

"Synthetic cannabis causes terrible problems in our communities and, in this case, we believe it was being supplied across the North Island," said Chambers.

The raids were a result of work by the Tauranga-based National Organised Crime Group and come as Parliament considers harsher penalties for those who supply synthetic cannabis.

Under the current law, manufacturing or possessing psychoactive substances for sale and supply carries a maximum sentence of two years in prison.

A bill to raise the maximum penalty to eight years passed its first reading in Parliament last month with the support of National and NZ First.

This would bring the maximum sentence into line with supplying a Class-C drug, such as cannabis.

The private member's bill of National MP Simeon Brown - opposed by Labour, the Greens and Act - has now been referred to select committee.

The bid to change the law was supported by the parents of a 22-year-old Auckland man whose addiction to synthetic cannabis killed him.

Calum Jones died in his family home last September - one of at least 25 deaths in 2017 linked to psychoactive substances.

However, critics say there was no evidence increasing penalties would reduce supply, or demand, of synthetic cannabis.

A review of the Psychoactive Substances Act was already planned for later this year.

Synthetic drugs became illegal 2014 following public concern about "legal highs" - designer drugs which mimicked the effects of cannabis - being sold in dairies.

Manufacturers of "legal highs" were making millions of dollars in a market which was completely unregulated.

Responding to public reaction, the government created a market where manufacturers had to prove the substances were 'low risk' with clinical testing.

Some were allowed to stay on shelves with an "interim exemption" but these were pulled after public outcry.

No manufacturers have carried on with clinical testing of products - which cost at least $2 million - since the amendment to the Psychoactive Substances Act in 2014

The ban pushed synthetic drugs underground and created a blackmarket with fatal consequences, according to new research.