A stockpile of methamphetamine allegedly worth $30 million was discussed by an Auckland-based Asian crime syndicate, court documents reveal.

The syndicate, made up in part of Chinese students, was caught dealing large quantities of the drug and found with hoards of cash during police raids last year - including one stash of more than $550,000 kept in a bank safety deposit box.

Police also found that one man had transferred more than $1.5 million back to China in a 22-month period.

Details of the police investigation - codenamed Operation Manu - were presented to the Auckland District Court yesterday during a depositions hearing to determine if there is enough evidence for the 13 defendants to go to trial.

Judge Graham Hubble allowed a Herald application to view the evidence handed up to the court.

A summary of the Operation Manu evidence shows police intercepted 3500 telephone calls in English, Mandarin and Cantonese.

In one conversation the accused Ri Tong Zhou said, "Still have over 30 Ks ... Just tell me how much you want, okay?"

The summary alleges Zhou is discussing 30kg of methamphetamine, with a street value of about $30 million.

The summary describes Zhou as a "large-scale dealer" in a syndicate that ultimately reported back to a leader in China who is not among the accused.

The leader had workers in New Zealand who were "custodians of his stockpile" and would control its sale to dealers like Zhou.

It would be released in kilogram amounts.

The summary says police caught a syndicate member with half a kilo of methamphetamine in October last year.

They seized another half kilo from a syndicate member's car in November, then found another half kilo in his apartment.

There were other smaller seizures of the drug.

Other evidence handed to the court shows Zhou, 38, is also known as "Four Eye Tong" and was a VIP member of Auckland's SkyCity casino, with one deposition saying he "appeared to have spent considerable time at SkyCity and gambled large amounts of cash at the venue".

Police also used a "covert search warrant" to examine the contents of a bank deposit box belonging to accused Zhong Wei, a 25-year-old known as "Visa" who is alleged to be one of the syndicate's controllers. Police photographs show stacks of $100 notes 6cm in height, with a later count showing $558,020 was held in the box.

A transaction history belonging to Wei showed he had transferred $1,566,136 back to China between January 2005 and October last year.