A man serving a life sentence for a gangland murder ran a methamphetamine supply ring by cellphone from inside Christchurch Men's Prison, a court was told today.

Dean Waka Nathan, pleaded guilty in Christchurch District Court to two related charges but disputed the amount of the drug involved.

Judge Stephen Erber remanded him in custody to October 8, when a date will be set for sentencing and a disputed facts hearing to decide the amount of the class A drug that was transported.

Nathan, now 42, was convicted in 2001 after a six week trial in the High Court at Christchurch for the drive-by shooting that killed Black Power gang member Max Shannon.

Nathan was one of four Highway 61 gang members convicted at the trial of gunning him down.

Crown prosecutor Claire Boshier agreed to withdraw a charge of conspiring to supply cannabis, when Nathan pleaded guilty to charges of supplying methamphetamine, and conspiring to supply the drug.

A total of nine people were charged at the end of the police's month long Operation Fudge investigation.

Some of those charged have already pleaded guilty and a depositions hearing is scheduled next month for others.

Police began the operation in January to investigate suspected drug dealing by Nathan involving the wholesale purchase of drugs in Auckland for sale in Christchurch.

They intercepted calls between Nathan using an unauthorised cellphone and others.

The Crown says Nathan organised someone to go to Auckland and buy methamphetamine at between $12,000 and $13,000 an ounce.

On one of these trips, a woman courier had $100,000 in cash with her.

The crown says up to 10 ounces of methamphetamine was purchased on these trips, and they say the courier made at least seven return flights to Auckland.

The crown also says the same woman drug courier made other trips by road and inter-island ferry.

When police executed their search warrants in February, Nathan declined to answer questions. The cellphone he had been using was not found during a search of his cell.