Southern police have unwittingly disclosed sensitive information about a major drug bust, but say it has not compromised the privacy or safety of those involved.
Area commander Inspector Lane Todd has confirmed police gave censored information to Operation Canary defendants through legal disclosure "which did not in part follow the normal process".
Those accused of offences in relation to Operation Canary - a multimillion-dollar cannabis bust targeting large-scale commercial growers in Queenstown and Southland - had asked for disclosure through the court.
They were provided with documents in a digital format and, as such, were able to uncover the parts police had tried to censor.
Mr Todd said, while the "appropriate and proper" editing was made to documents, it appeared the correct process was not followed in relation to how the documents were provided to defence lawyers.
"The process is that, in disclosures of this kind, a paper hard copy should be provided instead of an electronic copy. This did not happen in this instance," he said.
"While we do not believe that the privacy or safety of any individual has been compromised, police are taking this very seriously and an investigation is currently ongoing," Mr Todd said.
He would not comment on whether information about police informants had been accidentally made available to those facing charges as a result of the mishap, or whether the prosecution case had been compromised.
"Given this matter is still before the court, police are unable to discuss specifics in relation to what information was disclosed," he said.
Security of information was central to every aspect of police work and there were robust processes in place to protect information held by police, Mr Todd said.
"We believe this to be an isolated case. Once we have established the full facts of what happened we will obviously act on any learnings," he said.
A police spokeswoman said yesterday no further comment would be made in relation to the blunder "at this time".
Five men charged in relation to Operation Canary appeared in the Invercargill and Queenstown District Courts last year.
They are Invercargill accountant David Christopher Payne, Mossburn resident Brodie Raymond Anderson, Arthurs Point resident Brian Anthony McCarthy, Glenorchy resident Andrew John Grant and a 55-year-old Queenstown man, who was granted name suppression.
Collectively, they face more than 100 charges, including the possession and cultivation of cannabis for sale.
Police alleged the accused were part of a crime syndicate which had grown more than 1000 cannabis plants over a period of years, with a conservative estimate yield of 181kg of cannabis worth about $4.5 million.
About $1.8 million in assets, including three properties, a boat and two cars, were seized by police as part of the operation.