Police have seized synthetic cannabis worth hundreds of thousands of dollars and arrested five people – including a real estate agent and a chef – in a series of raids.

Police and the Organised Crime Taskforce searched 10 properties across Christchurch on Wednesday and Thursday as part of a major ongoing investigation dubbed Operation Sin.

They seized "significant amounts" of psychoactive substances and products used to manufacture the illegal drug, thousands of dollars in cash, and weapons, including a gun and a torch fitted with a Taser.

NZ POLICE Police netted hundreds of thousands of dollars in synthetic drugs in raids across Christchurch.

A black Mercedes Benz worth more than $100,000 was towed away from a house in Hei Hei Rd, in the suburb of Hei Hei, on Wednesday. Police will allege that a man who owns the property was a key player in a syndicate supplying synthetic drugs to parts of the South Island.

Police also raided a storage lock-up in Blenheim Rd late Wednesday where they found many large boxes full of synthetic drugs.

The bust is believed to be one of the largest of its kind in New Zealand. It is understood police will allege the syndicate was selling tens of thousands of dollars of drugs each month.

Xiwen Miao leaves the Christchurch District Court after facing charges relating to distributing synthetic cannabis.

READ MORE: Police seize $100,000 Mercedes Benz in Christchurch raids

Detective Senior Sergeant Jason Stewart said the large-scale operation blocked hundreds of thousands of dollars of synthetic drugs reaching the black market.

It had interrupted a major South Island supply chain, he said.

Sui Jun Zhou leaves the Christchurch District Court after facing charges relating to distributing synthetic cannabis.

Five people linked to the distribution network would appear in Christchurch District Court in the next fortnight, including:

– Sui Jun Zhou, a 31-year-old real estate agent. On Thursday, he was remanded on bail without plea on charges that he offered to sell a non-approved psycho-active substance in November, sold the substance in April, and possession of it for sale on Wednesday. He also faces three charges under the Arms Act alleging unlawful possession of a firearm and ammunition and possession of a restricted weapon – a torch fitted with a taser.

– Xiwen Miao, a 27-year-old chef from Avonhead. On Thursday, he was remanded on bail without plea on a charge that on Wednesday he possessed a non-approved psycho-active substance with intent to supply it.

Police discovered cash during the raids.

– A 27-year-old woman and 25-year-old man charged with supplying psychoactive substances.

– A 29-year-old woman charged with unlawful possession of a firearm.

Stewart said nationally fewer people were using synthetic drugs since they were made illegal in 2014, but a strong criminal market remained in Canterbury.

CHRISTOPHER ALLEN Police seize a black Mercedes Benz from a property in Hei Hei Rd, Hornby, Christchurch.

"There's still a perception that because some synthetic drugs used to be referred to as a legal high, that it was somehow not as bad for you as other drugs. That is absolutely not the case."

Side effects included psychosis, seizures and vomiting, he said.

"It's very addictive. The supply and consumption are driving other crimes to fund user's habits.

"Synthetic drugs seem to be particularly popular among our young people, who may not fully understand that there's no quality control on this material, and the exact ingredients and strengths are often unknown."

Manufacture and supply of synthetic cannabis went underground after the Government banned retailers from selling of psychoactive substances on May 8, 2014.

Synthetic cannabinoids are chemicals that mimic the 'high' THC in cannabis causes.

The drug had been the driving force behind some Christchurch criminals, including a 38-year-old burglar who had a $200-a-day habit.

Odyssey House youth services team leader Jim Marsters said the drug was popular among 14 to 16 year olds.

Youth who he treated found it more accessible and effective than cannabis, but highly addictive, he said.

"There is a need to get more, so they are ripping off their families, their neighbours, getting a mobile phone that's quite expensive and swapping it for the synthetic cannabis because they start to fein for it."

Marsters said when psychoactive substances were banned, people were already experimenting in making their own products. He believed more people were manufacturing products at home than importing them.

Retailers wanting to sell psychoactive substances – known as party pills, herbal highs, legal highs and synthetic cannabis – can apply for a licence to sell "approved products".

However, the Ministry of Health says products will likely not be approved for at least three years because of a ban preventing safety testing on animals.

Effectively, there are no approved products, so it is illegal to sell any synthetic cannabis.