Some police officers have been told not to reveal the nationality or ethnicity of drivers involved in fatal crashes.
But a media commentator says the withheld information is an "important part of the story" and needs to be supplied because of public interest.
An Official Information Act request revealed Southern road policing manager Inspector Tania Baron told police officers how to respond to media when asked if a driver in a serious or fatal crash was an overseas licence holder.
The request was sent after it became apparent police had become more reluctant to provide the nationality of drivers.
The latest Transport Agency data revealed overseas drivers were involved in about 6 per cent of fatal and injury crashes nationally, but the figure was much higher on Southern roads, totalling 27 per cent of fatal and injury crashes in Mackenzie, 25 per cent in Queenstown-Lakes, 24 per cent in Southland and 16 per cent in Central Otago.
Ms Baron gave officers the guidelines in October, telling them to refrain from commenting on the "nationality or ethnicity of drivers involved in crashes". She said the directive was exclusive to the Southern District - police districts worked independently and on orders relevant to each one.
In the guide, Ms Baron told officers to "formulate short responses" to any media at the scene. The responses should not mention ethnicity but refer to the injured or dead as a "mother or father, brother or sister, husband or wife, son or daughter".
Officers should talk about the continuing work of police, along the lines of: "Serious and fatal crashes require comprehensive investigations and it is too early to determine exactly what may have caused this crash". Officers could confirm the number of people involved in the crash and how many people died or were injured.
"Refrain from being drawn into comment on overseas licence holders as the initial investigation should be focused on what happened," she said in the guide.
The following phrase could be used: "The licence status of each driver will form part of our overall investigation, and police are unable to comment at present."
Massey University Adjunct Associate Professor Jim Tully, of Wellington, said there was "genuine public interest" in knowing if a driver involved in a crash was an overseas licence holder.
If a foreign driver showed a lack of familiarity with the New Zealand Road Code, such as by driving on the wrong side of the road, it was a significant road safety issue, he said.
"I can't see why you wouldn't make the nationality known because from a public interest point of view it's a significant part of the story."
He could not see how releasing the information would compromise a crash investigation.
Police revealed other details such as driver's age and gender, "so where is the big issue in terms of nationality".
Yesterday, Ms Baron said the "catalyst" for the guide was a police officer telling a reporter about a fatal crash in Luggate, in which a foreign driver failed to give way. The information the officer provided, such as the cause of the crash and the nationality of the driver, could have been accurate but they were not qualified to provide it. "They had summed up the crash before the investigation had taken place."
Southern police were concerned for the safety of visitors after foreign drivers were assaulted by vigilantes following media reports about fatal crashes, she said.
"The last thing we want to do is to attribute a crash to a certain nationality, when they could very well be New Zealand residents."