Three Chinese tourists were on their way from New Plymouth to Waitomo Caves, in the white car, when the crash happened on December 30.

A Chinese tourist hurt in a head-on crash had insult added to her extensive injuries when a police officer asked her why Chinese people were "so impatient".

The woman and two friends were injured - one critically, spending a week in a coma - when their car was hit by an oncoming vehicle which had crossed the centre line as they drove from New Plymouth to the Waitomo Caves on December 30, Chinese news website SkyKiwi reported.

After spending a month in hospital recovering, the woman texted the constable for an update on the investigation

A text message sent by a police officer to a Chinese tourist who was involved in a car crash.

"You said one month last time, why it takes so long?" she asked.

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"What's the rush?" the officer replied.

SUPPLIED The tourist driver swerved in an attempt to avoid an oncoming car on the wrong side of the road, a police crash report said. This image is included as a crash diagram.

"Investigations can take time, they need to ensure they are correct and everyone has been spoken to. Why are all the Chinese people involved so impatient?"

Police said comments made by the officer, a constable based at Mokau, 83km northwest of New Plymouth, were inappropriate.

"We demand the highest standards of integrity from our staff, in terms of judgement, choices and actions," they said in a statement.

SUPPLIED Mai Chen, of Chen Palmer, believes this kind of behaviour, while rare, can erode confidence in the police.

The story sparked a firestorm of comments on the SkyKiwi site, with some accusing the police of racism.

Mai Chen, managing partner of Chen Palmer Partners and chair of the Superdiversity Centre, said this kind of incident was concerning for people from different ethnicities and could be bad for tourism.

"It erodes confidence in the police, which is disappointing when so many officers I have met are professional, committed, empathetic and not racist.

A police traffic report from the crash involving three Chinese tourists and a New Plymouth driver.

"Unfortunately, the officer's response gives the impression that racism explains the lack of empathy and professionalism."

She praised the police response to the officer's comment.

A spokesperson for the Human Rights Commission said ethnicity didn't have anything to do with wanting a crash to be investigated.

Everyone should be treated with respect, the spokesperson said in a statement, but the commission couldn't comment much without being briefed on the ongoing investigation.

The injured woman, a front seat passenger, suffered a fractured sternum, compression fractures of her upper spine, a fractured wrist and a retrosternal haematoma, or blood collected in a pocket behind her fractured sternum.

Another passenger was even more badly hurt, spending a week in a coma, suffered severe organ damages, and has undergone multiple surgeries. The driver suffered minor injuries.

Before returning to Shanghai on Wednesday, the tourist who had the text exchange with the officer said she was frustrated at the slow pace of the police investigation.

She told SkyKiwi there had been plenty of cars around to witnesss the crash.

"My victim support also told me not to take the case to the court in New Zealand, because the lawyer would cost a fortune, and it will take at least two or three years," she said.

Police say the investigation into the crash is ongoing. According to a traffic crash report obtained by Stuff, the oncoming car driven by a New Plymouth local - had been driving on the wrong side of the road prior to the crash.

She told SkyKiwi there there were plenty of cars around to witness the crash, but the police investigation was progressing very slowly.