A gang boss has been stripped of his prized Harley Davidson motorcycle after he was caught trafficking hundreds of thousands of dollars' worth of methamphetamine into the Bay of Plenty.

Paul Christopher Laxon, 59, the South Island president of Mongrel Mob Notorious, was stopped by armed police as he travelled north towards Rotorua in a Ford Falcon on June 12 last year.

Police seized this Harley Davidson motorcycle from Paul Christopher Laxon. Photo: NZ Police.

He had flown to Rotorua from Christchurch the same day.

Investigators found 112 grams of methamphetamine (four ounces) in a plastic container hidden under carpet on the front passenger side of the car. The drugs had an estimated street value of $112,000.

Laxon, who had more than 60 historic convictions for an array of offences including drug dealing and burglary, was arrested as part of a covert sting codenamed Operation Mule. He faces a lengthy stretch behind bars.

According to court documents, investigators tapped phones and intercepted cellphone messages as they built a case against the gang leader and several other people over several months.

Laxon made at least six trips to the Bay of Plenty before his arrest, buying hundreds of thousands of dollars' worth of methamphetamine with cash, before returning to the South Island.

The drugs were distributed in Christchurch and Dunedin by a Mongrel Mob associate, a friend, and members of his family. Text messages showed Laxon was sometimes prepared to give women drugs in exchange for sex.

When police terminated the operation they found chemicals that could be used to manufacture methamphetamine at a property in St Albans.

Laxon admitted several charges, including supplying methamphetamine, an offence which carries a maximum penalty of life imprisonment. He is scheduled for sentencing at the Christchurch District Court on November 4.

Several other people – Karen Marie Scott, 44, Melissa Melanie-Jane Laxon (Paul Laxon's daughter), 38, Thomas Paul Christopher Neil (Paul Laxon's son) and Maynard Wickliffe, 37 – were also arrested as part of the operation and admitted supplying methamphetamine.

Scott was jailed in January for three years and two months, while Melissa Laxon was sentenced to 12 months' home detention last month.

Neil and Wickliffe will learn their fate on the same day as Paul Laxon.

Several months before his arrest, Laxon bought a Harley Davidson motorcycle for $14,500 cash from Christchurch Motorcycles.

Police seized the motorcycle the day after he was arrested on the basis it had been paid for using money made from drug dealing. It was later forfeited to the Crown.

Figures obtained from police show more than $300 million of assets, including cash, vehicles, jewellery and property, have been restrained by police under the Proceeds of Crime Act since 2010.

Police said large amounts of methamphetamine was being manufactured in the North Island and transported to the South Island, where it fetched a higher price.