Police officers are being stopped from taking media calls.
Southern district police commander Superintendent Mike Pannett made the order in a staff "advisory bulletin'' on March 7, an Official Information Act request has revealed.
"If you are contacted by media, especially printed media, please do not make verbal comment on any matters over the phone,'' Supt Pannett's email said.
"Please simply ask that all questions are put in an email and then sent to you. You can give the undertaking that someone will reply to those questions in due course.''
There is nothing in the directive stopping officers at crime and incident scenes from making comment and there are still daily face-to-face media briefings on weekdays.
A national media centre opened in Wellington last month.
Supt Pannett's email said police were having "challenges'' dealing with local media outlets, "in particular printed media'', who were calling individual staff members outside their normal working hours.
"While it is important we maintain a good working relationship with the local media, it is also important that we provide accurate, professional and well-researched answers to questions,'' the email said.
When contacted for comment, Supt Pannett said, in an emailed statement, his staff were taking a "growing number'' of media calls at home, late at night, and on issues they often knew nothing about.
The situation had improved since the national media centre began operating, he said.
"At this stage no further changes are envisaged.''
Otago Lakes-Central area head Inspector Olaf Jensen, who is based in Queenstown, discussed Supt Pannett's email at a leadership meeting on March 10.
However, Chris Kelley, the person in charge of Southern district's police official information, who is based in Dunedin, said: "No action points arose from the discussion and no meeting notes exist in relation to the media.''
Massey University associate professor of journalism Grant Hannis said important stories were broken through networking and contacts.
"To stage-manage the whole process there would be a real danger that it's going to lead to bland, non-committal comments that take a long time to get back to reporters and it is an erosion of that basic accountability of authorities to the Fourth Estate.''
On Tuesday, the Otago Daily Times broke news that southern police had been told to remain tight-lipped over the nationality of drivers involved in fatal crashes.